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  • Entity Framework 4 Entity with EntityState of Unchanged firing update

    - by Andy
    I am using EF 4, mapping all CUD operations for my entities using sprocs. I have two tables, ADDRESS and PERSON. A PERSON can have multiple ADDRESS associated with them. Here is the code I am running: Person person = (from p in context.People where p.PersonUID == 1 select p).FirstOrDefault(); Address address = (from a in context.Addresses where a.AddressUID == 51 select a).FirstOrDefault(); address.AddressLn2 = "Test"; context.SaveChanges(); The Address being updated is associated with the Person I am retrieveing - although they are not explicitly linked in any way in the code. When the context.SaveChanges() executes not only does the Update sproc for my Address entity get fired (like you would expect), but so does the Update sproc for the Person entity - even though you can see there was no change made to the Person entity. When I check the EntityState of both objects before the context.SaveChanges() call I see that my Address entity has an EntityState of "Modified" and my Person enity has an EntityState of "Unchanged". Why is the Update sproc being called for the Person entity? Is there a setting of some sort that I can set to prevent this from happening?

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  • What happens if I just add a second IP to a domain?

    - by tntu
    We have two servers that are in constant sync. We have two applications that connect to them. Each app to different server. We devised a new version of those apps that will read a dns entry and get a list of IP addresses and try them in order. Now problem is old apps. We have noticed that some ppl still use the old ones even if we have released the new. If we were to add two IP's to each domain would they receive the IP's in the order we set them or random? Either way it will still work for us but I'm just curious. If first server goes offline will the client application try the other? To be noted for old version: Interruption does not affect in any way the continuation once connection is reestablished. Each communication is independent of previous ones. Applications connect at set intervals of time anywhere between 5 seconds to 1 hour. Connection is done simply using an http post to the URL in question.

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  • Sending Email to a specific address without requiring user to specify their mail server details

    - by sgmoore
    Can anyone recommend a simple and reliable method of sending email notifications and possibly log files attachments from a C# program without requiring the installer or the user to configure the program by specifying server details and email addresses etc. (Mainly because they won't know the details, but also because they could change) The program will normally be run as a service of a Windows Server, but can be run on a client. I tried connecting to our own mail server and sending a email to myself, but some ISP's are blocking Port 25 on all servers but their own, so that method isn't working reliably. Tried sending email through gmail but that was less successful as the port they used was blocked by firewalls. Ditto webservices connecting on weird ports. Trying to use the local smptservice but did not work either. It would be nice, but not essential if it was not dependant on my own Internet connection/Servers. (Don't mind them being delayed, but prefer them not to get lost). Are there any webservices on http/https that allow you to do this sort of thing? TIA

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  • Why is Excel's 'Evaluate' method a general expression evaluator?

    - by jtolle
    A few questions have come up recently involving the Application.Evaluate method callable from Excel VBA. The old XLM macro language also exposes an EVALUATE() function. Both can be quite useful. Does anyone know why the evaluator that is exposed can handle general expressions, though? My own hunch is that Excel needed to give people a way to get ranges from string addresses, and to get the value of named formulas, and just opening a portal to the expression evaluator was the easiest way. (The help for the VBA version does say its purpose it to "convert a Microsoft Excel name to an object or a value".) But of course you don't need the ability to evaluate arbitrary expressions just to do that. (That is, Excel could provide a Name.Evaluate method or something instead.) Application.Evaluate seems kind of...unfinished. It's full behavior isn't very well documented, and there are quite a few quirks and limitations (as described by Charles Williams here: http://www.decisionmodels.com/calcsecretsh.htm) with what is exposed. I suppose the answer could be simply "why not expose it?", but I'd be interested to know what design decisions led to this feature taking the form that it does. Failing that, I'd be interested to hear other hunches.

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  • Within a DLL, how is the function table structured?

    - by Willi Ballenthin
    I've been looking into the implementation of a device library that doesn't explicitly support my operating system. In particular, I have a disassembled DLL, and a fair amount of supporting source code. Now, how is the function table/export table structured? My understanding is that the first structure of the .data section is a table of VRAs. Next is a table of strings linked by index to that first address table. This makes sense to me, as a linker could translate between symbols and addresses. How do functions referenced by ordinals fit into this picture? How does one know which function has such and such ordinal number, and how does the linker resolve this? In other words, given that some other DLL imports SOME_LIBRARY_ordinal_7, how does the linker know which function to work with? Thanks, all! edit More information... Im working with the FTDI libraries, and would like to resolve which function is being invoked. In particular, I see something like: extern FTD2XX_Ordinal_28: near how might I go about determining which function is being referenced, and how does the linker do this?

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  • Perl Script to search and replace in .SQL query file with user inputs

    - by T.Mount
    I have a .SQL file containing a large number of queries. They are being run against a database containing data for multiple states over multiple years. The machine I am running this on can only handle running the queries for one state, in one year, at a time. I am trying to create a Perl script that takes user input for the state abbreviation, the state id number, and the year. It then creates a directory for that state and year. Then it opens the "base" .SQL file and searches and replaces the base state id and year with the user input, and saves this new .SQL file to the created directory. The current script I have (below) stops at open(IN,'<$infile') with "Can't open [filename]" It seems that it is having difficulty finding or opening the .SQL file. I have quadruple-checked to make sure the paths are correct, and I have even tried replacing the $path with an absolute path for the base file. If it was having trouble with creating the new file I'd have more direction, but since it can't find/open the base file I do not know how to proceed. #!/usr/local/bin/perl use Cwd; $path = getcwd(); #Cleans up the path $path =~ s/\\/\//sg; #User inputs print "What is the 2 letter state abbreviation for the state? Ex. 'GA'\n"; $stlet = <>; print "What is the 2 digit state abbreviation for the state? Ex. '13'\n"; $stdig = <>; print "What four-digit year are you doing the calculations for? Ex. '2008'\n"; $year = <>; chomp $stlet; chomp $stdig; chomp $year; #Creates the directory mkdir($stlet); $new = $path."\/".$stlet; mkdir("$new/$year"); $infile = '$path/Base/TABLE_1-26.sql'; $outfile = '$path/$stlet/$year/TABLE_1-26.sql'; open(IN,'<$infile') or die "Can't open $infile: $!\n"; open(OUT,">$infile2") or die "Can't open $outfile: $!\n"; print "Working..."; while (my $search = <IN>) { chomp $search; $search =~ s/WHERE pop.grp = 132008/WHERE pop.grp = $stdig$year/g; print OUT "$search\n"; } close(IN); close(OUT); I know I also probably need to tweak the regular expression some, but I'm trying to take things one at a time. This is my first Perl script, and I haven't really been able to find anything that handles .SQL files like this that I can understand. Thank you!

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  • Joining tables with composite keys in a legacy system in hibernate

    - by Steve N
    Hi, I'm currently trying to create a pair of Hibernate annotated classes to load (read only) from a pair of tables in a legacy system. The legacy system uses a consistent (if somewhat dated) approach to keying tables. The tables I'm attempting to map are as follows: Customer CustomerAddress -------------------------- ---------------------------- customerNumber:string (pk) customerNumber:string (pk_1) name:string sequenceNumber:int (pk_2) street:string postalCode:string I've approached this by creating a CustomerAddress class like this: @Entity @Table(name="CustomerAddress") @IdClass(CustomerAddressKey.class) public class CustomerAddress { @Id @AttributeOverrides({ @AttributeOverride(name = "customerNumber", column = @Column(name="customerNumber")), @AttributeOverride(name = "sequenceNumber", column = @Column(name="sequenceNumber")) }) private String customerNumber; private int sequenceNumber; private String name; private String postalCode; ... } Where the CustomerAddressKey class is a simple Serializable object with the two key fields. The Customer object is then defined as: @Entity @Table(name = "Customer") public class Customer { private String customerNumber; private List<CustomerAddress> addresses = new ArrayList<CustomerAddress>(); private String name; ... } So, my question is: how do I express the OneToMany relationship on the Customer table?

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  • Google maps api Directions User defined Steps

    - by Via Lactea
    Hi All, I have a google map service with the stores mapped on it. I also have directions service (then you define two addresses or more and it shows you a way on this map, see google map api directions). So I wa?? to show the nearest stores to this way. Of course it could be the store located in the next streat of my way, so it also should be included to the list. So far I just found only an array of steps in the directions object which I get from google maps api. But these steps are predefined by google, so they can be too close one each to other and they also can be too far (if a part of your route is a highway or there is no any special steps on your way etc.) So, what I want to do. I want to make my own steps on the line that I get from google directions (for example to put these steps on my line every 500 meeters etc.), and after that to search every step for any stores around 200 meeters. Is it possible to do? I cannot find any solution of this idea in internet.

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  • fluent nhibernate - storing and retrieving three classes in/from one table

    - by Will I Am
    Noob question. I have this situation where I have these objects: class Address { string Street; string City; ... } class User { string UserID; Address BillingAddress; Address MailingAddress; ... } What is the proper way of storing this data using (fluent) nHibernate? I could use a separate Address table and create a reference, but they are 1:1 relationships so I don't really want to incur the overhead of a join. Ideally I would store this as a single flat record. So, my question is, what is the proper way of storing an instance of class 'User' in such a way that it stores its contents and also the two addresses as a single record? My knowledge is failing me on how I can store this information in such a way that the two Address records get different column names (e.g. BillingAddress_Street and MailingAddress_Street, for example), and also how to read a record back into a User instance.

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  • Difference between the address space of parent process and its child process in Linux?

    - by abbas1707
    Hi, I am confused about it. I have read that when a child is created by a parent process, child gets a copy of its parent's address space. What it means here by copy? If i use code below, then it prints same addresses of variable 'a' which is on heap in all cases. i.e in case of child and parent. So what is happening here? #include <sys/types.h> #include <stdio.h> #include <unistd.h> #include <stdlib.h> int main () { pid_t pid; int *a = (int *)malloc(4); printf ("heap pointer %p\n", a); pid = fork(); if (pid < 0) { fprintf (stderr, "Fork Failed"); exit(-1); } else if (pid == 0) { printf ("Child\n"); printf ("in child heap pointer %p\n", a); } else { wait (NULL); printf ("Child Complete\n"); printf ("in parent heap pointer %p\n", a); exit(0); } }

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  • CakePHP - recursive on specific fields in model?

    - by Paul
    Hi, I'm pretty new to CakePHP but I think I'm starting to get the hang of it. I'm trying to pull related table information recursively, but I want to specify which related models to recurse on. Let me give you an example to demonstrate my goal: I have a model "Customer", which has info like Company name, website, etc. "Customer" hasMany "Addresses", which contain info for individual contacts like Contact Name, Street, City, State, Country, etc. "Customer" also belongsTo "CustomerType", which is just has descriptive category info - a name and description, like "Distributor" or "Manufacturer". When I do a find on "Customer" I want to get associated "CustomerType" and "Address" info as sub-arrays, and this works fine just by setting up the hasMany and belongsTo associations properly. But now, here's my issue: I want to get associated State/Country info. So, instead of each "Address" array row just having "state_id", I want it to have "state" = array("id" = 20, "name" = "New York",...) etc. If I set $recursive to a higher value (e.g., 2) in the Partner model, I get what I want for the State/Country info in each "Address". BUT it also recurses on "CustomerType", and that results in the "CustomerType" field of my "Partner" object having a huge array of all Customer objects that match that type, which could be thousands long. So the point is, I DON'T want to recurse on "CustomerType", only on "Address". Is there a way I can set this up? Sorry for the long-winded question, and thanks in advance!

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  • Getting a stream back from a .Net remoting service that is accessible with IP v4 and v6

    - by jon.ediger
    My company has an existing .Net Remoting service that listens on a port, fronting interfaces used by external systems. This all works great with IP v4 based communications. However, this service now needs to support both IP v4 communications and IP v6 communications. I have found info that the system.runtime.remoting section of the app.config should include two channels as follows: <channel ref="tcp" name="tcp6" port="9000" bindTo="[::]" /> <channel ref="tcp" name="tcp4" port="9000" bindTo="0.0.0.0" /> The above config file changes to the System.Runtime.Remoting config section will get the remoting service responding to non-stream functions on both ip v4 and ip v6. The issue comes only when attempting to get a stream back, used to upload or download large files. In this case, instead of getting a usable stream back, the following ArgumentException is thrown instead: IPv4 address 0.0.0.0 and IPv6 address ::0 are unspecified addresses that cannot be used as a target address. Parameter name: hostNameOrAddress Is there a way to modify the app.config (in the system.runtime.remoting section, or another section) so that the service will return a stream mapped to a real ip so the client can actually upload/download files while maintaining the ability to use both IP v4 and IP v6?

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  • Rails Nested Attributes Doesn't Insert ID Correctly

    - by MunkiPhD
    I'm attempting to edit a model's nested attributes, much as outline here, replicated here: <%= form_for @person do |person_form| %> <%= person_form.text_field :name %> <% for address in @person.addresses %> <%= person_form.fields_for address, :index => address do |address_form|%> <%= address_form.text_field :city %> <% end %> <% end %> <% end %> In my code, I have the following: <%= form_for(@meal) do |f| %> <!-- some other stuff that's irrelevant... --> <% for subitem in @meal.meal_line_items %> <%= f.fields_for subitem, :index => subitem do |line_item_form| %> <%= line_item_form.label :servings %><br/> <%= line_item_form.text_field :servings %><br/> <%= line_item_form.label :food_id %><br/> <%= line_item_form.text_field :food_id %><br/> <% end %> <% end %> <%= f.submit %> <% end %> This works great, except, when I look at the HTML, it's creating the inputs that look like the following, failing to input the correct id and instead placing the memory representation(?) of the model: <input type="text" value="2" size="30" name="meal[meal_line_item][#<MealLineItem:0x00000005c5d618>][servings]" id="meal_meal_line_item_#<MealLineItem:0x00000005c5d618>_servings">

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  • Allocating 32-bit integer arrays in 64-bit machines

    - by Shredderroy
    I have a 64-bit i7 machine. Suppose I allocate memory for n 32-bit integers. How many physical registers will actually be used in the allocation: n, or n/2? I tried to write the following simple programme to find out. #include <iostream> #include <cstdlib> using namespace std; int main (int argc, char *argv[]) { int a[4]; cout << &a[0] << "\t" << &a[3] << endl; cin.ignore (1); return 0; } // End main () The output is: 0018FA04 0018FA10 They seem further apart than they should be. Why aren't the addresses 04 and 07? And does this mean that the system is actually allocating four (or more) integers, instead of packing the four 32-bit integers into two 64-bit registers? Thanks in advance for your help.

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  • Memory fragmentation @ boost::asio ?

    - by Poni
    I'm pretty much stuck with a question I never got an answer for, a question which addresses an extremely important issue; memory fragmentation at boost::asio. Found nothing at the documentation nor here at SO. The functions at boost::asio, for example async_write() & async_read_some() always allocate something. (in my case it's 144 & 96 bytes respectively, in VC9 Debug build). How do I know about it? I connect a client to the "echo server" example provided with this library. I put a breakpoint at "new.cpp" at the code of "operator new(size_t size)". Then I send "123". Breakpoint is hit! Now using the stack trace I can clearly see that the root to the "new" call is coming from the async_write() & async_read_some() calls I make in the function handlers. So memory fragmentation will come sooner or later, thus I can't use ASIO, and I wish I could! Any idea? Any helpful code example?

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  • How can solve "Cross-thread operation not valid"?

    - by Phsika
    i try to start multi Thread but i can not it returns to me error: Cross-thread operation not valid: 'listBox1' thread was created to control outside access from another thread was. MyCodes: public DataTable dTable; public DataTable dtRowsCount; Thread t1; ThreadStart ts1; void ExcelToSql() { // SelectDataFromExcel(); ts1 = new ThreadStart(SelectDataFromExcel); t1 = new Thread(ts1); t1.Start(); } void SelectDataFromExcel() { string connectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Source\Addresses.xlsx;Extended Properties=""Excel 12.0;HDR=YES;"""; OleDbConnection excelConnection = new OleDbConnection(connectionString); string[] Sheets = new string[] { "Sayfa1"}; excelConnection.Open(); // This code will open excel file. OleDbCommand dbCommand; OleDbDataAdapter dataAdapter; // progressBar1.Minimum = 1; foreach (var sheet in Sheets) { dbCommand = new OleDbCommand("select * From[" + sheet + "$]", excelConnection); //progressBar1.Maximum = CountRowsExcel(sheet).Rows.Count; // progressBar2.Value = i + 1; System.Threading.Thread.Sleep(1000); **listBox1.Items.Add("Tablo ismi: "+sheet.ToUpper()+"Satir Adeti: "+CountRowsExcel(sheet).Rows.Count.ToString()+" ");** dataAdapter = new OleDbDataAdapter(dbCommand); dTable = new DataTable(); dataAdapter.Fill(dTable); dTable.TableName = sheet.ToUpper(); dTable.Dispose(); dataAdapter.Dispose(); dbCommand.Dispose(); ArrangedDataList(dTable); FillSqlTable(dTable, dTable.TableName); } excelConnection.Close(); excelConnection.Dispose(); }

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  • How can I write output to a new external file with Perl?

    - by Structure
    Maybe I am searching with the wrong keywords or this is a very basic question but I cannot find the answer to my question. I am having trouble writing the result of my whois command to a new external file. My code is below. It takes $readfilename, which is a file name which has a list of IPs, and $writefilename, which is the destination file for output. Both are user-specified. For my tests, $readfilename contains three IP addresses on three separate lines so there should be three separate whois results in the user specified output file. if ($readfilename) { open (my $inputfile, "<", $readfilename) || die "\n Cannot open the specified file. Please double check your file name and path.\n\n"; open (my $outputfile, ">", $writefilename) || die "\n Could not create write file.\n\n"; while (<$inputfile>) { my $iplookupresult = `whois $_`; print $outputfile $iplookupresult; } close $outputfile; close $inputfile; } I can execute this script and end up with a new external file, but over half of the file has binary garbage data (running on CentOS) and only one (or a portion of one) of the whois lookups is readable. I have no idea how half of my file is ending up binary... but my approach must be incorrect. Is there a better way to achieve the same result?

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  • load different images for each item on the listbox

    - by user161179
    Javascript: function changeMap() { imagesource = "http://maps.google.com/maps/api/staticmap?size=500x500&maptype=hybrid&zoom=16&sensor=false&markers=color:blue|label:K|28.541250,77.204100" ; mapimage.src = imagesource ; } Html code : <select name="choose_colony" id="choose_colony" size="8" onchange="changeMap()" style="float: left;"> <option value="1" >Big apartments</option> . . <option value="999">plaza</option> </select> <img name="mapimage" src="" alt="Select your Colony" style="float: right;"> In this whenever a selection on the listbox is made changeMap is called and an image is loaded. What I want is for a different image to be loaded everytime depending upon the option selected . there will be over 2000 entries in the listbox. Considering this what is the best way of going about this ? I can figure out the if/then part , but my main question is whether its ok to put all the 2000 long image addresses in the html file itself ? I hope I was clear ..

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  • Zen and the Art of File and Folder Organization

    - by Mark Virtue
    Is your desk a paragon of neatness, or does it look like a paper-bomb has gone off? If you’ve been putting off getting organized because the task is too huge or daunting, or you don’t know where to start, we’ve got 40 tips to get you on the path to zen mastery of your filing system. For all those readers who would like to get their files and folders organized, or, if they’re already organized, better organized—we have compiled a complete guide to getting organized and staying organized, a comprehensive article that will hopefully cover every possible tip you could want. Signs that Your Computer is Poorly Organized If your computer is a mess, you’re probably already aware of it.  But just in case you’re not, here are some tell-tale signs: Your Desktop has over 40 icons on it “My Documents” contains over 300 files and 60 folders, including MP3s and digital photos You use the Windows’ built-in search facility whenever you need to find a file You can’t find programs in the out-of-control list of programs in your Start Menu You save all your Word documents in one folder, all your spreadsheets in a second folder, etc Any given file that you’re looking for may be in any one of four different sets of folders But before we start, here are some quick notes: We’re going to assume you know what files and folders are, and how to create, save, rename, copy and delete them The organization principles described in this article apply equally to all computer systems.  However, the screenshots here will reflect how things look on Windows (usually Windows 7).  We will also mention some useful features of Windows that can help you get organized. Everyone has their own favorite methodology of organizing and filing, and it’s all too easy to get into “My Way is Better than Your Way” arguments.  The reality is that there is no perfect way of getting things organized.  When I wrote this article, I tried to keep a generalist and objective viewpoint.  I consider myself to be unusually well organized (to the point of obsession, truth be told), and I’ve had 25 years experience in collecting and organizing files on computers.  So I’ve got a lot to say on the subject.  But the tips I have described here are only one way of doing it.  Hopefully some of these tips will work for you too, but please don’t read this as any sort of “right” way to do it. At the end of the article we’ll be asking you, the reader, for your own organization tips. Why Bother Organizing At All? For some, the answer to this question is self-evident. And yet, in this era of powerful desktop search software (the search capabilities built into the Windows Vista and Windows 7 Start Menus, and third-party programs like Google Desktop Search), the question does need to be asked, and answered. I have a friend who puts every file he ever creates, receives or downloads into his My Documents folder and doesn’t bother filing them into subfolders at all.  He relies on the search functionality built into his Windows operating system to help him find whatever he’s looking for.  And he always finds it.  He’s a Search Samurai.  For him, filing is a waste of valuable time that could be spent enjoying life! It’s tempting to follow suit.  On the face of it, why would anyone bother to take the time to organize their hard disk when such excellent search software is available?  Well, if all you ever want to do with the files you own is to locate and open them individually (for listening, editing, etc), then there’s no reason to ever bother doing one scrap of organization.  But consider these common tasks that are not achievable with desktop search software: Find files manually.  Often it’s not convenient, speedy or even possible to utilize your desktop search software to find what you want.  It doesn’t work 100% of the time, or you may not even have it installed.  Sometimes its just plain faster to go straight to the file you want, if you know it’s in a particular sub-folder, rather than trawling through hundreds of search results. Find groups of similar files (e.g. all your “work” files, all the photos of your Europe holiday in 2008, all your music videos, all the MP3s from Dark Side of the Moon, all your letters you wrote to your wife, all your tax returns).  Clever naming of the files will only get you so far.  Sometimes it’s the date the file was created that’s important, other times it’s the file format, and other times it’s the purpose of the file.  How do you name a collection of files so that they’re easy to isolate based on any of the above criteria?  Short answer, you can’t. Move files to a new computer.  It’s time to upgrade your computer.  How do you quickly grab all the files that are important to you?  Or you decide to have two computers now – one for home and one for work.  How do you quickly isolate only the work-related files to move them to the work computer? Synchronize files to other computers.  If you have more than one computer, and you need to mirror some of your files onto the other computer (e.g. your music collection), then you need a way to quickly determine which files are to be synced and which are not.  Surely you don’t want to synchronize everything? Choose which files to back up.  If your backup regime calls for multiple backups, or requires speedy backups, then you’ll need to be able to specify which files are to be backed up, and which are not.  This is not possible if they’re all in the same folder. Finally, if you’re simply someone who takes pleasure in being organized, tidy and ordered (me! me!), then you don’t even need a reason.  Being disorganized is simply unthinkable. Tips on Getting Organized Here we present our 40 best tips on how to get organized.  Or, if you’re already organized, to get better organized. Tip #1.  Choose Your Organization System Carefully The reason that most people are not organized is that it takes time.  And the first thing that takes time is deciding upon a system of organization.  This is always a matter of personal preference, and is not something that a geek on a website can tell you.  You should always choose your own system, based on how your own brain is organized (which makes the assumption that your brain is, in fact, organized). We can’t instruct you, but we can make suggestions: You may want to start off with a system based on the users of the computer.  i.e. “My Files”, “My Wife’s Files”, My Son’s Files”, etc.  Inside “My Files”, you might then break it down into “Personal” and “Business”.  You may then realize that there are overlaps.  For example, everyone may want to share access to the music library, or the photos from the school play.  So you may create another folder called “Family”, for the “common” files. You may decide that the highest-level breakdown of your files is based on the “source” of each file.  In other words, who created the files.  You could have “Files created by ME (business or personal)”, “Files created by people I know (family, friends, etc)”, and finally “Files created by the rest of the world (MP3 music files, downloaded or ripped movies or TV shows, software installation files, gorgeous desktop wallpaper images you’ve collected, etc).”  This system happens to be the one I use myself.  See below:  Mark is for files created by meVC is for files created by my company (Virtual Creations)Others is for files created by my friends and familyData is the rest of the worldAlso, Settings is where I store the configuration files and other program data files for my installed software (more on this in tip #34, below). Each folder will present its own particular set of requirements for further sub-organization.  For example, you may decide to organize your music collection into sub-folders based on the artist’s name, while your digital photos might get organized based on the date they were taken.  It can be different for every sub-folder! Another strategy would be based on “currentness”.  Files you have yet to open and look at live in one folder.  Ones that have been looked at but not yet filed live in another place.  Current, active projects live in yet another place.  All other files (your “archive”, if you like) would live in a fourth folder. (And of course, within that last folder you’d need to create a further sub-system based on one of the previous bullet points). Put some thought into this – changing it when it proves incomplete can be a big hassle!  Before you go to the trouble of implementing any system you come up with, examine a wide cross-section of the files you own and see if they will all be able to find a nice logical place to sit within your system. Tip #2.  When You Decide on Your System, Stick to It! There’s nothing more pointless than going to all the trouble of creating a system and filing all your files, and then whenever you create, receive or download a new file, you simply dump it onto your Desktop.  You need to be disciplined – forever!  Every new file you get, spend those extra few seconds to file it where it belongs!  Otherwise, in just a month or two, you’ll be worse off than before – half your files will be organized and half will be disorganized – and you won’t know which is which! Tip #3.  Choose the Root Folder of Your Structure Carefully Every data file (document, photo, music file, etc) that you create, own or is important to you, no matter where it came from, should be found within one single folder, and that one single folder should be located at the root of your C: drive (as a sub-folder of C:\).  In other words, do not base your folder structure in standard folders like “My Documents”.  If you do, then you’re leaving it up to the operating system engineers to decide what folder structure is best for you.  And every operating system has a different system!  In Windows 7 your files are found in C:\Users\YourName, whilst on Windows XP it was C:\Documents and Settings\YourName\My Documents.  In UNIX systems it’s often /home/YourName. These standard default folders tend to fill up with junk files and folders that are not at all important to you.  “My Documents” is the worst offender.  Every second piece of software you install, it seems, likes to create its own folder in the “My Documents” folder.  These folders usually don’t fit within your organizational structure, so don’t use them!  In fact, don’t even use the “My Documents” folder at all.  Allow it to fill up with junk, and then simply ignore it.  It sounds heretical, but: Don’t ever visit your “My Documents” folder!  Remove your icons/links to “My Documents” and replace them with links to the folders you created and you care about! Create your own file system from scratch!  Probably the best place to put it would be on your D: drive – if you have one.  This way, all your files live on one drive, while all the operating system and software component files live on the C: drive – simply and elegantly separated.  The benefits of that are profound.  Not only are there obvious organizational benefits (see tip #10, below), but when it comes to migrate your data to a new computer, you can (sometimes) simply unplug your D: drive and plug it in as the D: drive of your new computer (this implies that the D: drive is actually a separate physical disk, and not a partition on the same disk as C:).  You also get a slight speed improvement (again, only if your C: and D: drives are on separate physical disks). Warning:  From tip #12, below, you will see that it’s actually a good idea to have exactly the same file system structure – including the drive it’s filed on – on all of the computers you own.  So if you decide to use the D: drive as the storage system for your own files, make sure you are able to use the D: drive on all the computers you own.  If you can’t ensure that, then you can still use a clever geeky trick to store your files on the D: drive, but still access them all via the C: drive (see tip #17, below). If you only have one hard disk (C:), then create a dedicated folder that will contain all your files – something like C:\Files.  The name of the folder is not important, but make it a single, brief word. There are several reasons for this: When creating a backup regime, it’s easy to decide what files should be backed up – they’re all in the one folder! If you ever decide to trade in your computer for a new one, you know exactly which files to migrate You will always know where to begin a search for any file If you synchronize files with other computers, it makes your synchronization routines very simple.   It also causes all your shortcuts to continue to work on the other machines (more about this in tip #24, below). Once you’ve decided where your files should go, then put all your files in there – Everything!  Completely disregard the standard, default folders that are created for you by the operating system (“My Music”, “My Pictures”, etc).  In fact, you can actually relocate many of those folders into your own structure (more about that below, in tip #6). The more completely you get all your data files (documents, photos, music, etc) and all your configuration settings into that one folder, then the easier it will be to perform all of the above tasks. Once this has been done, and all your files live in one folder, all the other folders in C:\ can be thought of as “operating system” folders, and therefore of little day-to-day interest for us. Here’s a screenshot of a nicely organized C: drive, where all user files are located within the \Files folder:   Tip #4.  Use Sub-Folders This would be our simplest and most obvious tip.  It almost goes without saying.  Any organizational system you decide upon (see tip #1) will require that you create sub-folders for your files.  Get used to creating folders on a regular basis. Tip #5.  Don’t be Shy About Depth Create as many levels of sub-folders as you need.  Don’t be scared to do so.  Every time you notice an opportunity to group a set of related files into a sub-folder, do so.  Examples might include:  All the MP3s from one music CD, all the photos from one holiday, or all the documents from one client. It’s perfectly okay to put files into a folder called C:\Files\Me\From Others\Services\WestCo Bank\Statements\2009.  That’s only seven levels deep.  Ten levels is not uncommon.  Of course, it’s possible to take this too far.  If you notice yourself creating a sub-folder to hold only one file, then you’ve probably become a little over-zealous.  On the other hand, if you simply create a structure with only two levels (for example C:\Files\Work) then you really haven’t achieved any level of organization at all (unless you own only six files!).  Your “Work” folder will have become a dumping ground, just like your Desktop was, with most likely hundreds of files in it. Tip #6.  Move the Standard User Folders into Your Own Folder Structure Most operating systems, including Windows, create a set of standard folders for each of its users.  These folders then become the default location for files such as documents, music files, digital photos and downloaded Internet files.  In Windows 7, the full list is shown below: Some of these folders you may never use nor care about (for example, the Favorites folder, if you’re not using Internet Explorer as your browser).  Those ones you can leave where they are.  But you may be using some of the other folders to store files that are important to you.  Even if you’re not using them, Windows will still often treat them as the default storage location for many types of files.  When you go to save a standard file type, it can become annoying to be automatically prompted to save it in a folder that’s not part of your own file structure. But there’s a simple solution:  Move the folders you care about into your own folder structure!  If you do, then the next time you go to save a file of the corresponding type, Windows will prompt you to save it in the new, moved location. Moving the folders is easy.  Simply drag-and-drop them to the new location.  Here’s a screenshot of the default My Music folder being moved to my custom personal folder (Mark): Tip #7.  Name Files and Folders Intelligently This is another one that almost goes without saying, but we’ll say it anyway:  Do not allow files to be created that have meaningless names like Document1.doc, or folders called New Folder (2).  Take that extra 20 seconds and come up with a meaningful name for the file/folder – one that accurately divulges its contents without repeating the entire contents in the name. Tip #8.  Watch Out for Long Filenames Another way to tell if you have not yet created enough depth to your folder hierarchy is that your files often require really long names.  If you need to call a file Johnson Sales Figures March 2009.xls (which might happen to live in the same folder as Abercrombie Budget Report 2008.xls), then you might want to create some sub-folders so that the first file could be simply called March.xls, and living in the Clients\Johnson\Sales Figures\2009 folder. A well-placed file needs only a brief filename! Tip #9.  Use Shortcuts!  Everywhere! This is probably the single most useful and important tip we can offer.  A shortcut allows a file to be in two places at once. Why would you want that?  Well, the file and folder structure of every popular operating system on the market today is hierarchical.  This means that all objects (files and folders) always live within exactly one parent folder.  It’s a bit like a tree.  A tree has branches (folders) and leaves (files).  Each leaf, and each branch, is supported by exactly one parent branch, all the way back to the root of the tree (which, incidentally, is exactly why C:\ is called the “root folder” of the C: drive). That hard disks are structured this way may seem obvious and even necessary, but it’s only one way of organizing data.  There are others:  Relational databases, for example, organize structured data entirely differently.  The main limitation of hierarchical filing structures is that a file can only ever be in one branch of the tree – in only one folder – at a time.  Why is this a problem?  Well, there are two main reasons why this limitation is a problem for computer users: The “correct” place for a file, according to our organizational rationale, is very often a very inconvenient place for that file to be located.  Just because it’s correctly filed doesn’t mean it’s easy to get to.  Your file may be “correctly” buried six levels deep in your sub-folder structure, but you may need regular and speedy access to this file every day.  You could always move it to a more convenient location, but that would mean that you would need to re-file back to its “correct” location it every time you’d finished working on it.  Most unsatisfactory. A file may simply “belong” in two or more different locations within your file structure.  For example, say you’re an accountant and you have just completed the 2009 tax return for John Smith.  It might make sense to you to call this file 2009 Tax Return.doc and file it under Clients\John Smith.  But it may also be important to you to have the 2009 tax returns from all your clients together in the one place.  So you might also want to call the file John Smith.doc and file it under Tax Returns\2009.  The problem is, in a purely hierarchical filing system, you can’t put it in both places.  Grrrrr! Fortunately, Windows (and most other operating systems) offers a way for you to do exactly that:  It’s called a “shortcut” (also known as an “alias” on Macs and a “symbolic link” on UNIX systems).  Shortcuts allow a file to exist in one place, and an icon that represents the file to be created and put anywhere else you please.  In fact, you can create a dozen such icons and scatter them all over your hard disk.  Double-clicking on one of these icons/shortcuts opens up the original file, just as if you had double-clicked on the original file itself. Consider the following two icons: The one on the left is the actual Word document, while the one on the right is a shortcut that represents the Word document.  Double-clicking on either icon will open the same file.  There are two main visual differences between the icons: The shortcut will have a small arrow in the lower-left-hand corner (on Windows, anyway) The shortcut is allowed to have a name that does not include the file extension (the “.docx” part, in this case) You can delete the shortcut at any time without losing any actual data.  The original is still intact.  All you lose is the ability to get to that data from wherever the shortcut was. So why are shortcuts so great?  Because they allow us to easily overcome the main limitation of hierarchical file systems, and put a file in two (or more) places at the same time.  You will always have files that don’t play nice with your organizational rationale, and can’t be filed in only one place.  They demand to exist in two places.  Shortcuts allow this!  Furthermore, they allow you to collect your most often-opened files and folders together in one spot for convenient access.  The cool part is that the original files stay where they are, safe forever in their perfectly organized location. So your collection of most often-opened files can – and should – become a collection of shortcuts! If you’re still not convinced of the utility of shortcuts, consider the following well-known areas of a typical Windows computer: The Start Menu (and all the programs that live within it) The Quick Launch bar (or the Superbar in Windows 7) The “Favorite folders” area in the top-left corner of the Windows Explorer window (in Windows Vista or Windows 7) Your Internet Explorer Favorites or Firefox Bookmarks Each item in each of these areas is a shortcut!  Each of those areas exist for one purpose only:  For convenience – to provide you with a collection of the files and folders you access most often. It should be easy to see by now that shortcuts are designed for one single purpose:  To make accessing your files more convenient.  Each time you double-click on a shortcut, you are saved the hassle of locating the file (or folder, or program, or drive, or control panel icon) that it represents. Shortcuts allow us to invent a golden rule of file and folder organization: “Only ever have one copy of a file – never have two copies of the same file.  Use a shortcut instead” (this rule doesn’t apply to copies created for backup purposes, of course!) There are also lesser rules, like “don’t move a file into your work area – create a shortcut there instead”, and “any time you find yourself frustrated with how long it takes to locate a file, create a shortcut to it and place that shortcut in a convenient location.” So how to we create these massively useful shortcuts?  There are two main ways: “Copy” the original file or folder (click on it and type Ctrl-C, or right-click on it and select Copy):  Then right-click in an empty area of the destination folder (the place where you want the shortcut to go) and select Paste shortcut: Right-drag (drag with the right mouse button) the file from the source folder to the destination folder.  When you let go of the mouse button at the destination folder, a menu pops up: Select Create shortcuts here. Note that when shortcuts are created, they are often named something like Shortcut to Budget Detail.doc (windows XP) or Budget Detail – Shortcut.doc (Windows 7).   If you don’t like those extra words, you can easily rename the shortcuts after they’re created, or you can configure Windows to never insert the extra words in the first place (see our article on how to do this). And of course, you can create shortcuts to folders too, not just to files! Bottom line: Whenever you have a file that you’d like to access from somewhere else (whether it’s convenience you’re after, or because the file simply belongs in two places), create a shortcut to the original file in the new location. Tip #10.  Separate Application Files from Data Files Any digital organization guru will drum this rule into you.  Application files are the components of the software you’ve installed (e.g. Microsoft Word, Adobe Photoshop or Internet Explorer).  Data files are the files that you’ve created for yourself using that software (e.g. Word Documents, digital photos, emails or playlists). Software gets installed, uninstalled and upgraded all the time.  Hopefully you always have the original installation media (or downloaded set-up file) kept somewhere safe, and can thus reinstall your software at any time.  This means that the software component files are of little importance.  Whereas the files you have created with that software is, by definition, important.  It’s a good rule to always separate unimportant files from important files. So when your software prompts you to save a file you’ve just created, take a moment and check out where it’s suggesting that you save the file.  If it’s suggesting that you save the file into the same folder as the software itself, then definitely don’t follow that suggestion.  File it in your own folder!  In fact, see if you can find the program’s configuration option that determines where files are saved by default (if it has one), and change it. Tip #11.  Organize Files Based on Purpose, Not on File Type If you have, for example a folder called Work\Clients\Johnson, and within that folder you have two sub-folders, Word Documents and Spreadsheets (in other words, you’re separating “.doc” files from “.xls” files), then chances are that you’re not optimally organized.  It makes little sense to organize your files based on the program that created them.  Instead, create your sub-folders based on the purpose of the file.  For example, it would make more sense to create sub-folders called Correspondence and Financials.  It may well be that all the files in a given sub-folder are of the same file-type, but this should be more of a coincidence and less of a design feature of your organization system. Tip #12.  Maintain the Same Folder Structure on All Your Computers In other words, whatever organizational system you create, apply it to every computer that you can.  There are several benefits to this: There’s less to remember.  No matter where you are, you always know where to look for your files If you copy or synchronize files from one computer to another, then setting up the synchronization job becomes very simple Shortcuts can be copied or moved from one computer to another with ease (assuming the original files are also copied/moved).  There’s no need to find the target of the shortcut all over again on the second computer Ditto for linked files (e.g Word documents that link to data in a separate Excel file), playlists, and any files that reference the exact file locations of other files. This applies even to the drive that your files are stored on.  If your files are stored on C: on one computer, make sure they’re stored on C: on all your computers.  Otherwise all your shortcuts, playlists and linked files will stop working! Tip #13.  Create an “Inbox” Folder Create yourself a folder where you store all files that you’re currently working on, or that you haven’t gotten around to filing yet.  You can think of this folder as your “to-do” list.  You can call it “Inbox” (making it the same metaphor as your email system), or “Work”, or “To-Do”, or “Scratch”, or whatever name makes sense to you.  It doesn’t matter what you call it – just make sure you have one! Once you have finished working on a file, you then move it from the “Inbox” to its correct location within your organizational structure. You may want to use your Desktop as this “Inbox” folder.  Rightly or wrongly, most people do.  It’s not a bad place to put such files, but be careful:  If you do decide that your Desktop represents your “to-do” list, then make sure that no other files find their way there.  In other words, make sure that your “Inbox”, wherever it is, Desktop or otherwise, is kept free of junk – stray files that don’t belong there. So where should you put this folder, which, almost by definition, lives outside the structure of the rest of your filing system?  Well, first and foremost, it has to be somewhere handy.  This will be one of your most-visited folders, so convenience is key.  Putting it on the Desktop is a great option – especially if you don’t have any other folders on your Desktop:  the folder then becomes supremely easy to find in Windows Explorer: You would then create shortcuts to this folder in convenient spots all over your computer (“Favorite Links”, “Quick Launch”, etc). Tip #14.  Ensure You have Only One “Inbox” Folder Once you’ve created your “Inbox” folder, don’t use any other folder location as your “to-do list”.  Throw every incoming or created file into the Inbox folder as you create/receive it.  This keeps the rest of your computer pristine and free of randomly created or downloaded junk.  The last thing you want to be doing is checking multiple folders to see all your current tasks and projects.  Gather them all together into one folder. Here are some tips to help ensure you only have one Inbox: Set the default “save” location of all your programs to this folder. Set the default “download” location for your browser to this folder. If this folder is not your desktop (recommended) then also see if you can make a point of not putting “to-do” files on your desktop.  This keeps your desktop uncluttered and Zen-like: (the Inbox folder is in the bottom-right corner) Tip #15.  Be Vigilant about Clearing Your “Inbox” Folder This is one of the keys to staying organized.  If you let your “Inbox” overflow (i.e. allow there to be more than, say, 30 files or folders in there), then you’re probably going to start feeling like you’re overwhelmed:  You’re not keeping up with your to-do list.  Once your Inbox gets beyond a certain point (around 30 files, studies have shown), then you’ll simply start to avoid it.  You may continue to put files in there, but you’ll be scared to look at it, fearing the “out of control” feeling that all overworked, chaotic or just plain disorganized people regularly feel. So, here’s what you can do: Visit your Inbox/to-do folder regularly (at least five times per day). Scan the folder regularly for files that you have completed working on and are ready for filing.  File them immediately. Make it a source of pride to keep the number of files in this folder as small as possible.  If you value peace of mind, then make the emptiness of this folder one of your highest (computer) priorities If you know that a particular file has been in the folder for more than, say, six weeks, then admit that you’re not actually going to get around to processing it, and move it to its final resting place. Tip #16.  File Everything Immediately, and Use Shortcuts for Your Active Projects As soon as you create, receive or download a new file, store it away in its “correct” folder immediately.  Then, whenever you need to work on it (possibly straight away), create a shortcut to it in your “Inbox” (“to-do”) folder or your desktop.  That way, all your files are always in their “correct” locations, yet you still have immediate, convenient access to your current, active files.  When you finish working on a file, simply delete the shortcut. Ideally, your “Inbox” folder – and your Desktop – should contain no actual files or folders.  They should simply contain shortcuts. Tip #17.  Use Directory Symbolic Links (or Junctions) to Maintain One Unified Folder Structure Using this tip, we can get around a potential hiccup that we can run into when creating our organizational structure – the issue of having more than one drive on our computer (C:, D:, etc).  We might have files we need to store on the D: drive for space reasons, and yet want to base our organized folder structure on the C: drive (or vice-versa). Your chosen organizational structure may dictate that all your files must be accessed from the C: drive (for example, the root folder of all your files may be something like C:\Files).  And yet you may still have a D: drive and wish to take advantage of the hundreds of spare Gigabytes that it offers.  Did you know that it’s actually possible to store your files on the D: drive and yet access them as if they were on the C: drive?  And no, we’re not talking about shortcuts here (although the concept is very similar). By using the shell command mklink, you can essentially take a folder that lives on one drive and create an alias for it on a different drive (you can do lots more than that with mklink – for a full rundown on this programs capabilities, see our dedicated article).  These aliases are called directory symbolic links (and used to be known as junctions).  You can think of them as “virtual” folders.  They function exactly like regular folders, except they’re physically located somewhere else. For example, you may decide that your entire D: drive contains your complete organizational file structure, but that you need to reference all those files as if they were on the C: drive, under C:\Files.  If that was the case you could create C:\Files as a directory symbolic link – a link to D:, as follows: mklink /d c:\files d:\ Or it may be that the only files you wish to store on the D: drive are your movie collection.  You could locate all your movie files in the root of your D: drive, and then link it to C:\Files\Media\Movies, as follows: mklink /d c:\files\media\movies d:\ (Needless to say, you must run these commands from a command prompt – click the Start button, type cmd and press Enter) Tip #18. Customize Your Folder Icons This is not strictly speaking an organizational tip, but having unique icons for each folder does allow you to more quickly visually identify which folder is which, and thus saves you time when you’re finding files.  An example is below (from my folder that contains all files downloaded from the Internet): To learn how to change your folder icons, please refer to our dedicated article on the subject. Tip #19.  Tidy Your Start Menu The Windows Start Menu is usually one of the messiest parts of any Windows computer.  Every program you install seems to adopt a completely different approach to placing icons in this menu.  Some simply put a single program icon.  Others create a folder based on the name of the software.  And others create a folder based on the name of the software manufacturer.  It’s chaos, and can make it hard to find the software you want to run. Thankfully we can avoid this chaos with useful operating system features like Quick Launch, the Superbar or pinned start menu items. Even so, it would make a lot of sense to get into the guts of the Start Menu itself and give it a good once-over.  All you really need to decide is how you’re going to organize your applications.  A structure based on the purpose of the application is an obvious candidate.  Below is an example of one such structure: In this structure, Utilities means software whose job it is to keep the computer itself running smoothly (configuration tools, backup software, Zip programs, etc).  Applications refers to any productivity software that doesn’t fit under the headings Multimedia, Graphics, Internet, etc. In case you’re not aware, every icon in your Start Menu is a shortcut and can be manipulated like any other shortcut (copied, moved, deleted, etc). With the Windows Start Menu (all version of Windows), Microsoft has decided that there be two parallel folder structures to store your Start Menu shortcuts.  One for you (the logged-in user of the computer) and one for all users of the computer.  Having two parallel structures can often be redundant:  If you are the only user of the computer, then having two parallel structures is totally redundant.  Even if you have several users that regularly log into the computer, most of your installed software will need to be made available to all users, and should thus be moved out of the “just you” version of the Start Menu and into the “all users” area. To take control of your Start Menu, so you can start organizing it, you’ll need to know how to access the actual folders and shortcut files that make up the Start Menu (both versions of it).  To find these folders and files, click the Start button and then right-click on the All Programs text (Windows XP users should right-click on the Start button itself): The Open option refers to the “just you” version of the Start Menu, while the Open All Users option refers to the “all users” version.  Click on the one you want to organize. A Windows Explorer window then opens with your chosen version of the Start Menu selected.  From there it’s easy.  Double-click on the Programs folder and you’ll see all your folders and shortcuts.  Now you can delete/rename/move until it’s just the way you want it. Note:  When you’re reorganizing your Start Menu, you may want to have two Explorer windows open at the same time – one showing the “just you” version and one showing the “all users” version.  You can drag-and-drop between the windows. Tip #20.  Keep Your Start Menu Tidy Once you have a perfectly organized Start Menu, try to be a little vigilant about keeping it that way.  Every time you install a new piece of software, the icons that get created will almost certainly violate your organizational structure. So to keep your Start Menu pristine and organized, make sure you do the following whenever you install a new piece of software: Check whether the software was installed into the “just you” area of the Start Menu, or the “all users” area, and then move it to the correct area. Remove all the unnecessary icons (like the “Read me” icon, the “Help” icon (you can always open the help from within the software itself when it’s running), the “Uninstall” icon, the link(s)to the manufacturer’s website, etc) Rename the main icon(s) of the software to something brief that makes sense to you.  For example, you might like to rename Microsoft Office Word 2010 to simply Word Move the icon(s) into the correct folder based on your Start Menu organizational structure And don’t forget:  when you uninstall a piece of software, the software’s uninstall routine is no longer going to be able to remove the software’s icon from the Start Menu (because you moved and/or renamed it), so you’ll need to remove that icon manually. Tip #21.  Tidy C:\ The root of your C: drive (C:\) is a common dumping ground for files and folders – both by the users of your computer and by the software that you install on your computer.  It can become a mess. There’s almost no software these days that requires itself to be installed in C:\.  99% of the time it can and should be installed into C:\Program Files.  And as for your own files, well, it’s clear that they can (and almost always should) be stored somewhere else. In an ideal world, your C:\ folder should look like this (on Windows 7): Note that there are some system files and folders in C:\ that are usually and deliberately “hidden” (such as the Windows virtual memory file pagefile.sys, the boot loader file bootmgr, and the System Volume Information folder).  Hiding these files and folders is a good idea, as they need to stay where they are and are almost never needed to be opened or even seen by you, the user.  Hiding them prevents you from accidentally messing with them, and enhances your sense of order and well-being when you look at your C: drive folder. Tip #22.  Tidy Your Desktop The Desktop is probably the most abused part of a Windows computer (from an organization point of view).  It usually serves as a dumping ground for all incoming files, as well as holding icons to oft-used applications, plus some regularly opened files and folders.  It often ends up becoming an uncontrolled mess.  See if you can avoid this.  Here’s why… Application icons (Word, Internet Explorer, etc) are often found on the Desktop, but it’s unlikely that this is the optimum place for them.  The “Quick Launch” bar (or the Superbar in Windows 7) is always visible and so represents a perfect location to put your icons.  You’ll only be able to see the icons on your Desktop when all your programs are minimized.  It might be time to get your application icons off your desktop… You may have decided that the Inbox/To-do folder on your computer (see tip #13, above) should be your Desktop.  If so, then enough said.  Simply be vigilant about clearing it and preventing it from being polluted by junk files (see tip #15, above).  On the other hand, if your Desktop is not acting as your “Inbox” folder, then there’s no reason for it to have any data files or folders on it at all, except perhaps a couple of shortcuts to often-opened files and folders (either ongoing or current projects).  Everything else should be moved to your “Inbox” folder. In an ideal world, it might look like this: Tip #23.  Move Permanent Items on Your Desktop Away from the Top-Left Corner When files/folders are dragged onto your desktop in a Windows Explorer window, or when shortcuts are created on your Desktop from Internet Explorer, those icons are always placed in the top-left corner – or as close as they can get.  If you have other files, folders or shortcuts that you keep on the Desktop permanently, then it’s a good idea to separate these permanent icons from the transient ones, so that you can quickly identify which ones the transients are.  An easy way to do this is to move all your permanent icons to the right-hand side of your Desktop.  That should keep them separated from incoming items. Tip #24.  Synchronize If you have more than one computer, you’ll almost certainly want to share files between them.  If the computers are permanently attached to the same local network, then there’s no need to store multiple copies of any one file or folder – shortcuts will suffice.  However, if the computers are not always on the same network, then you will at some point need to copy files between them.  For files that need to permanently live on both computers, the ideal way to do this is to synchronize the files, as opposed to simply copying them. We only have room here to write a brief summary of synchronization, not a full article.  In short, there are several different types of synchronization: Where the contents of one folder are accessible anywhere, such as with Dropbox Where the contents of any number of folders are accessible anywhere, such as with Windows Live Mesh Where any files or folders from anywhere on your computer are synchronized with exactly one other computer, such as with the Windows “Briefcase”, Microsoft SyncToy, or (much more powerful, yet still free) SyncBack from 2BrightSparks.  This only works when both computers are on the same local network, at least temporarily. A great advantage of synchronization solutions is that once you’ve got it configured the way you want it, then the sync process happens automatically, every time.  Click a button (or schedule it to happen automatically) and all your files are automagically put where they’re supposed to be. If you maintain the same file and folder structure on both computers, then you can also sync files depend upon the correct location of other files, like shortcuts, playlists and office documents that link to other office documents, and the synchronized files still work on the other computer! Tip #25.  Hide Files You Never Need to See If you have your files well organized, you will often be able to tell if a file is out of place just by glancing at the contents of a folder (for example, it should be pretty obvious if you look in a folder that contains all the MP3s from one music CD and see a Word document in there).  This is a good thing – it allows you to determine if there are files out of place with a quick glance.  Yet sometimes there are files in a folder that seem out of place but actually need to be there, such as the “folder art” JPEGs in music folders, and various files in the root of the C: drive.  If such files never need to be opened by you, then a good idea is to simply hide them.  Then, the next time you glance at the folder, you won’t have to remember whether that file was supposed to be there or not, because you won’t see it at all! To hide a file, simply right-click on it and choose Properties: Then simply tick the Hidden tick-box:   Tip #26.  Keep Every Setup File These days most software is downloaded from the Internet.  Whenever you download a piece of software, keep it.  You’ll never know when you need to reinstall the software. Further, keep with it an Internet shortcut that links back to the website where you originally downloaded it, in case you ever need to check for updates. See tip #33 below for a full description of the excellence of organizing your setup files. Tip #27.  Try to Minimize the Number of Folders that Contain Both Files and Sub-folders Some of the folders in your organizational structure will contain only files.  Others will contain only sub-folders.  And you will also have some folders that contain both files and sub-folders.  You will notice slight improvements in how long it takes you to locate a file if you try to avoid this third type of folder.  It’s not always possible, of course – you’ll always have some of these folders, but see if you can avoid it. One way of doing this is to take all the leftover files that didn’t end up getting stored in a sub-folder and create a special “Miscellaneous” or “Other” folder for them. Tip #28.  Starting a Filename with an Underscore Brings it to the Top of a List Further to the previous tip, if you name that “Miscellaneous” or “Other” folder in such a way that its name begins with an underscore “_”, then it will appear at the top of the list of files/folders. The screenshot below is an example of this.  Each folder in the list contains a set of digital photos.  The folder at the top of the list, _Misc, contains random photos that didn’t deserve their own dedicated folder: Tip #29.  Clean Up those CD-ROMs and (shudder!) Floppy Disks Have you got a pile of CD-ROMs stacked on a shelf of your office?  Old photos, or files you archived off onto CD-ROM (or even worse, floppy disks!) because you didn’t have enough disk space at the time?  In the meantime have you upgraded your computer and now have 500 Gigabytes of space you don’t know what to do with?  If so, isn’t it time you tidied up that stack of disks and filed them into your gorgeous new folder structure? So what are you waiting for?  Bite the bullet, copy them all back onto your computer, file them in their appropriate folders, and then back the whole lot up onto a shiny new 1000Gig external hard drive! Useful Folders to Create This next section suggests some useful folders that you might want to create within your folder structure.  I’ve personally found them to be indispensable. The first three are all about convenience – handy folders to create and then put somewhere that you can always access instantly.  For each one, it’s not so important where the actual folder is located, but it’s very important where you put the shortcut(s) to the folder.  You might want to locate the shortcuts: On your Desktop In your “Quick Launch” area (or pinned to your Windows 7 Superbar) In your Windows Explorer “Favorite Links” area Tip #30.  Create an “Inbox” (“To-Do”) Folder This has already been mentioned in depth (see tip #13), but we wanted to reiterate its importance here.  This folder contains all the recently created, received or downloaded files that you have not yet had a chance to file away properly, and it also may contain files that you have yet to process.  In effect, it becomes a sort of “to-do list”.  It doesn’t have to be called “Inbox” – you can call it whatever you want. Tip #31.  Create a Folder where Your Current Projects are Collected Rather than going hunting for them all the time, or dumping them all on your desktop, create a special folder where you put links (or work folders) for each of the projects you’re currently working on. You can locate this folder in your “Inbox” folder, on your desktop, or anywhere at all – just so long as there’s a way of getting to it quickly, such as putting a link to it in Windows Explorer’s “Favorite Links” area: Tip #32.  Create a Folder for Files and Folders that You Regularly Open You will always have a few files that you open regularly, whether it be a spreadsheet of your current accounts, or a favorite playlist.  These are not necessarily “current projects”, rather they’re simply files that you always find yourself opening.  Typically such files would be located on your desktop (or even better, shortcuts to those files).  Why not collect all such shortcuts together and put them in their own special folder? As with the “Current Projects” folder (above), you would want to locate that folder somewhere convenient.  Below is an example of a folder called “Quick links”, with about seven files (shortcuts) in it, that is accessible through the Windows Quick Launch bar: See tip #37 below for a full explanation of the power of the Quick Launch bar. Tip #33.  Create a “Set-ups” Folder A typical computer has dozens of applications installed on it.  For each piece of software, there are often many different pieces of information you need to keep track of, including: The original installation setup file(s).  This can be anything from a simple 100Kb setup.exe file you downloaded from a website, all the way up to a 4Gig ISO file that you copied from a DVD-ROM that you purchased. The home page of the software manufacturer (in case you need to look up something on their support pages, their forum or their online help) The page containing the download link for your actual file (in case you need to re-download it, or download an upgraded version) The serial number Your proof-of-purchase documentation Any other template files, plug-ins, themes, etc that also need to get installed For each piece of software, it’s a great idea to gather all of these files together and put them in a single folder.  The folder can be the name of the software (plus possibly a very brief description of what it’s for – in case you can’t remember what the software does based in its name).  Then you would gather all of these folders together into one place, and call it something like “Software” or “Setups”. If you have enough of these folders (I have several hundred, being a geek, collected over 20 years), then you may want to further categorize them.  My own categorization structure is based on “platform” (operating system): The last seven folders each represents one platform/operating system, while _Operating Systems contains set-up files for installing the operating systems themselves.  _Hardware contains ROMs for hardware I own, such as routers. Within the Windows folder (above), you can see the beginnings of the vast library of software I’ve compiled over the years: An example of a typical application folder looks like this: Tip #34.  Have a “Settings” Folder We all know that our documents are important.  So are our photos and music files.  We save all of these files into folders, and then locate them afterwards and double-click on them to open them.  But there are many files that are important to us that can’t be saved into folders, and then searched for and double-clicked later on.  These files certainly contain important information that we need, but are often created internally by an application, and saved wherever that application feels is appropriate. A good example of this is the “PST” file that Outlook creates for us and uses to store all our emails, contacts, appointments and so forth.  Another example would be the collection of Bookmarks that Firefox stores on your behalf. And yet another example would be the customized settings and configuration files of our all our software.  Granted, most Windows programs store their configuration in the Registry, but there are still many programs that use configuration files to store their settings. Imagine if you lost all of the above files!  And yet, when people are backing up their computers, they typically only back up the files they know about – those that are stored in the “My Documents” folder, etc.  If they had a hard disk failure or their computer was lost or stolen, their backup files would not include some of the most vital files they owned.  Also, when migrating to a new computer, it’s vital to ensure that these files make the journey. It can be a very useful idea to create yourself a folder to store all your “settings” – files that are important to you but which you never actually search for by name and double-click on to open them.  Otherwise, next time you go to set up a new computer just the way you want it, you’ll need to spend hours recreating the configuration of your previous computer! So how to we get our important files into this folder?  Well, we have a few options: Some programs (such as Outlook and its PST files) allow you to place these files wherever you want.  If you delve into the program’s options, you will find a setting somewhere that controls the location of the important settings files (or “personal storage” – PST – when it comes to Outlook) Some programs do not allow you to change such locations in any easy way, but if you get into the Registry, you can sometimes find a registry key that refers to the location of the file(s).  Simply move the file into your Settings folder and adjust the registry key to refer to the new location. Some programs stubbornly refuse to allow their settings files to be placed anywhere other then where they stipulate.  When faced with programs like these, you have three choices:  (1) You can ignore those files, (2) You can copy the files into your Settings folder (let’s face it – settings don’t change very often), or (3) you can use synchronization software, such as the Windows Briefcase, to make synchronized copies of all your files in your Settings folder.  All you then have to do is to remember to run your sync software periodically (perhaps just before you run your backup software!). There are some other things you may decide to locate inside this new “Settings” folder: Exports of registry keys (from the many applications that store their configurations in the Registry).  This is useful for backup purposes or for migrating to a new computer Notes you’ve made about all the specific customizations you have made to a particular piece of software (so that you’ll know how to do it all again on your next computer) Shortcuts to webpages that detail how to tweak certain aspects of your operating system or applications so they are just the way you like them (such as how to remove the words “Shortcut to” from the beginning of newly created shortcuts).  In other words, you’d want to create shortcuts to half the pages on the How-To Geek website! Here’s an example of a “Settings” folder: Windows Features that Help with Organization This section details some of the features of Microsoft Windows that are a boon to anyone hoping to stay optimally organized. Tip #35.  Use the “Favorite Links” Area to Access Oft-Used Folders Once you’ve created your great new filing system, work out which folders you access most regularly, or which serve as great starting points for locating the rest of the files in your folder structure, and then put links to those folders in your “Favorite Links” area of the left-hand side of the Windows Explorer window (simply called “Favorites” in Windows 7):   Some ideas for folders you might want to add there include: Your “Inbox” folder (or whatever you’ve called it) – most important! The base of your filing structure (e.g. C:\Files) A folder containing shortcuts to often-accessed folders on other computers around the network (shown above as Network Folders) A folder containing shortcuts to your current projects (unless that folder is in your “Inbox” folder) Getting folders into this area is very simple – just locate the folder you’re interested in and drag it there! Tip #36.  Customize the Places Bar in the File/Open and File/Save Boxes Consider the screenshot below: The highlighted icons (collectively known as the “Places Bar”) can be customized to refer to any folder location you want, allowing instant access to any part of your organizational structure. Note:  These File/Open and File/Save boxes have been superseded by new versions that use the Windows Vista/Windows 7 “Favorite Links”, but the older versions (shown above) are still used by a surprisingly large number of applications. The easiest way to customize these icons is to use the Group Policy Editor, but not everyone has access to this program.  If you do, open it up and navigate to: User Configuration > Administrative Templates > Windows Components > Windows Explorer > Common Open File Dialog If you don’t have access to the Group Policy Editor, then you’ll need to get into the Registry.  Navigate to: HKEY_CURRENT_USER \ Software \ Microsoft  \ Windows \ CurrentVersion \ Policies \ comdlg32 \ Placesbar It should then be easy to make the desired changes.  Log off and log on again to allow the changes to take effect. Tip #37.  Use the Quick Launch Bar as a Application and File Launcher That Quick Launch bar (to the right of the Start button) is a lot more useful than people give it credit for.  Most people simply have half a dozen icons in it, and use it to start just those programs.  But it can actually be used to instantly access just about anything in your filing system: For complete instructions on how to set this up, visit our dedicated article on this topic. Tip #38.  Put a Shortcut to Windows Explorer into Your Quick Launch Bar This is only necessary in Windows Vista and Windows XP.  The Microsoft boffins finally got wise and added it to the Windows 7 Superbar by default. Windows Explorer – the program used for managing your files and folders – is one of the most useful programs in Windows.  Anyone who considers themselves serious about being organized needs instant access to this program at any time.  A great place to create a shortcut to this program is in the Windows XP and Windows Vista “Quick Launch” bar: To get it there, locate it in your Start Menu (usually under “Accessories”) and then right-drag it down into your Quick Launch bar (and create a copy). Tip #39.  Customize the Starting Folder for Your Windows 7 Explorer Superbar Icon If you’re on Windows 7, your Superbar will include a Windows Explorer icon.  Clicking on the icon will launch Windows Explorer (of course), and will start you off in your “Libraries” folder.  Libraries may be fine as a starting point, but if you have created yourself an “Inbox” folder, then it would probably make more sense to start off in this folder every time you launch Windows Explorer. To change this default/starting folder location, then first right-click the Explorer icon in the Superbar, and then right-click Properties:Then, in Target field of the Windows Explorer Properties box that appears, type %windir%\explorer.exe followed by the path of the folder you wish to start in.  For example: %windir%\explorer.exe C:\Files If that folder happened to be on the Desktop (and called, say, “Inbox”), then you would use the following cleverness: %windir%\explorer.exe shell:desktop\Inbox Then click OK and test it out. Tip #40.  Ummmmm…. No, that’s it.  I can’t think of another one.  That’s all of the tips I can come up with.  I only created this one because 40 is such a nice round number… Case Study – An Organized PC To finish off the article, I have included a few screenshots of my (main) computer (running Vista).  The aim here is twofold: To give you a sense of what it looks like when the above, sometimes abstract, tips are applied to a real-life computer, and To offer some ideas about folders and structure that you may want to steal to use on your own PC. Let’s start with the C: drive itself.  Very minimal.  All my files are contained within C:\Files.  I’ll confine the rest of the case study to this folder: That folder contains the following: Mark: My personal files VC: My business (Virtual Creations, Australia) Others contains files created by friends and family Data contains files from the rest of the world (can be thought of as “public” files, usually downloaded from the Net) Settings is described above in tip #34 The Data folder contains the following sub-folders: Audio:  Radio plays, audio books, podcasts, etc Development:  Programmer and developer resources, sample source code, etc (see below) Humour:  Jokes, funnies (those emails that we all receive) Movies:  Downloaded and ripped movies (all legal, of course!), their scripts, DVD covers, etc. Music:  (see below) Setups:  Installation files for software (explained in full in tip #33) System:  (see below) TV:  Downloaded TV shows Writings:  Books, instruction manuals, etc (see below) The Music folder contains the following sub-folders: Album covers:  JPEG scans Guitar tabs:  Text files of guitar sheet music Lists:  e.g. “Top 1000 songs of all time” Lyrics:  Text files MIDI:  Electronic music files MP3 (representing 99% of the Music folder):  MP3s, either ripped from CDs or downloaded, sorted by artist/album name Music Video:  Video clips Sheet Music:  usually PDFs The Data\Writings folder contains the following sub-folders: (all pretty self-explanatory) The Data\Development folder contains the following sub-folders: Again, all pretty self-explanatory (if you’re a geek) The Data\System folder contains the following sub-folders: These are usually themes, plug-ins and other downloadable program-specific resources. The Mark folder contains the following sub-folders: From Others:  Usually letters that other people (friends, family, etc) have written to me For Others:  Letters and other things I have created for other people Green Book:  None of your business Playlists:  M3U files that I have compiled of my favorite songs (plus one M3U playlist file for every album I own) Writing:  Fiction, philosophy and other musings of mine Mark Docs:  Shortcut to C:\Users\Mark Settings:  Shortcut to C:\Files\Settings\Mark The Others folder contains the following sub-folders: The VC (Virtual Creations, my business – I develop websites) folder contains the following sub-folders: And again, all of those are pretty self-explanatory. Conclusion These tips have saved my sanity and helped keep me a productive geek, but what about you? What tips and tricks do you have to keep your files organized?  Please share them with us in the comments.  Come on, don’t be shy… Similar Articles Productive Geek Tips Fix For When Windows Explorer in Vista Stops Showing File NamesWhy Did Windows Vista’s Music Folder Icon Turn Yellow?Print or Create a Text File List of the Contents in a Directory the Easy WayCustomize the Windows 7 or Vista Send To MenuAdd Copy To / Move To on Windows 7 or Vista Right-Click Menu TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Acronis Online Backup DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows Track Daily Goals With 42Goals Video Toolbox is a Superb Online Video Editor Fun with 47 charts and graphs Tomorrow is Mother’s Day Check the Average Speed of YouTube Videos You’ve Watched OutlookStatView Scans and Displays General Usage Statistics

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  • Followup: Python 2.6, 3 abstract base class misunderstanding

    - by Aaron
    I asked a question at Python 2.6, 3 abstract base class misunderstanding. My problem was that python abstract base classes didn't work quite the way I expected them to. There was some discussion in the comments about why I would want to use ABCs at all, and Alex Martelli provided an excellent answer on why my use didn't work and how to accomplish what I wanted. Here I'd like to address why one might want to use ABCs, and show my test code implementation based on Alex's answer. tl;dr: Code after the 16th paragraph. In the discussion on the original post, statements were made along the lines that you don't need ABCs in Python, and that ABCs don't do anything and are therefore not real classes; they're merely interface definitions. An abstract base class is just a tool in your tool box. It's a design tool that's been around for many years, and a programming tool that is explicitly available in many programming languages. It can be implemented manually in languages that don't provide it. An ABC is always a real class, even when it doesn't do anything but define an interface, because specifying the interface is what an ABC does. If that was all an ABC could do, that would be enough reason to have it in your toolbox, but in Python and some other languages they can do more. The basic reason to use an ABC is when you have a number of classes that all do the same thing (have the same interface) but do it differently, and you want to guarantee that that complete interface is implemented in all objects. A user of your classes can rely on the interface being completely implemented in all classes. You can maintain this guarantee manually. Over time you may succeed. Or you might forget something. Before Python had ABCs you could guarantee it semi-manually, by throwing NotImplementedError in all the base class's interface methods; you must implement these methods in derived classes. This is only a partial solution, because you can still instantiate such a base class. A more complete solution is to use ABCs as provided in Python 2.6 and above. Template methods and other wrinkles and patterns are ideas whose implementation can be made easier with full-citizen ABCs. Another idea in the comments was that Python doesn't need ABCs (understood as a class that only defines an interface) because it has multiple inheritance. The implied reference there seems to be Java and its single inheritance. In Java you "get around" single inheritance by inheriting from one or more interfaces. Java uses the word "interface" in two ways. A "Java interface" is a class with method signatures but no implementations. The methods are the interface's "interface" in the more general, non-Java sense of the word. Yes, Python has multiple inheritance, so you don't need Java-like "interfaces" (ABCs) merely to provide sets of interface methods to a class. But that's not the only reason in software development to use ABCs. Most generally, you use an ABC to specify an interface (set of methods) that will likely be implemented differently in different derived classes, yet that all derived classes must have. Additionally, there may be no sensible default implementation for the base class to provide. Finally, even an ABC with almost no interface is still useful. We use something like it when we have multiple except clauses for a try. Many exceptions have exactly the same interface, with only two differences: the exception's string value, and the actual class of the exception. In many exception clauses we use nothing about the exception except its class to decide what to do; catching one type of exception we do one thing, and another except clause catching a different exception does another thing. According to the exception module's doc page, BaseException is not intended to be derived by any user defined exceptions. If ABCs had been a first class Python concept from the beginning, it's easy to imagine BaseException being specified as an ABC. But enough of that. Here's some 2.6 code that demonstrates how to use ABCs, and how to specify a list-like ABC. Examples are run in ipython, which I like much better than the python shell for day to day work; I only wish it was available for python3. Your basic 2.6 ABC: from abc import ABCMeta, abstractmethod class Super(): __metaclass__ = ABCMeta @abstractmethod def method1(self): pass Test it (in ipython, python shell would be similar): In [2]: a = Super() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Super with abstract methods method1 Notice the end of the last line, where the TypeError exception tells us that method1 has not been implemented ("abstract methods method1"). That was the method designated as @abstractmethod in the preceding code. Create a subclass that inherits Super, implement method1 in the subclass and you're done. My problem, which caused me to ask the original question, was how to specify an ABC that itself defines a list interface. My naive solution was to make an ABC as above, and in the inheritance parentheses say (list). My assumption was that the class would still be abstract (can't instantiate it), and would be a list. That was wrong; inheriting from list made the class concrete, despite the abstract bits in the class definition. Alex suggested inheriting from collections.MutableSequence, which is abstract (and so doesn't make the class concrete) and list-like. I used collections.Sequence, which is also abstract but has a shorter interface and so was quicker to implement. First, Super derived from Sequence, with nothing extra: from abc import abstractmethod from collections import Sequence class Super(Sequence): pass Test it: In [6]: a = Super() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Super with abstract methods __getitem__, __len__ We can't instantiate it. A list-like full-citizen ABC; yea! Again, notice in the last line that TypeError tells us why we can't instantiate it: __getitem__ and __len__ are abstract methods. They come from collections.Sequence. But, I want a bunch of subclasses that all act like immutable lists (which collections.Sequence essentially is), and that have their own implementations of my added interface methods. In particular, I don't want to implement my own list code, Python already did that for me. So first, let's implement the missing Sequence methods, in terms of Python's list type, so that all subclasses act as lists (Sequences). First let's see the signatures of the missing abstract methods: In [12]: help(Sequence.__getitem__) Help on method __getitem__ in module _abcoll: __getitem__(self, index) unbound _abcoll.Sequence method (END) In [14]: help(Sequence.__len__) Help on method __len__ in module _abcoll: __len__(self) unbound _abcoll.Sequence method (END) __getitem__ takes an index, and __len__ takes nothing. And the implementation (so far) is: from abc import abstractmethod from collections import Sequence class Super(Sequence): # Gives us a list member for ABC methods to use. def __init__(self): self._list = [] # Abstract method in Sequence, implemented in terms of list. def __getitem__(self, index): return self._list.__getitem__(index) # Abstract method in Sequence, implemented in terms of list. def __len__(self): return self._list.__len__() # Not required. Makes printing behave like a list. def __repr__(self): return self._list.__repr__() Test it: In [34]: a = Super() In [35]: a Out[35]: [] In [36]: print a [] In [37]: len(a) Out[37]: 0 In [38]: a[0] --------------------------------------------------------------------------- IndexError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() /home/aaron/projects/test/test.py in __getitem__(self, index) 10 # Abstract method in Sequence, implemented in terms of list. 11 def __getitem__(self, index): ---> 12 return self._list.__getitem__(index) 13 14 # Abstract method in Sequence, implemented in terms of list. IndexError: list index out of range Just like a list. It's not abstract (for the moment) because we implemented both of Sequence's abstract methods. Now I want to add my bit of interface, which will be abstract in Super and therefore required to implement in any subclasses. And we'll cut to the chase and add subclasses that inherit from our ABC Super. from abc import abstractmethod from collections import Sequence class Super(Sequence): # Gives us a list member for ABC methods to use. def __init__(self): self._list = [] # Abstract method in Sequence, implemented in terms of list. def __getitem__(self, index): return self._list.__getitem__(index) # Abstract method in Sequence, implemented in terms of list. def __len__(self): return self._list.__len__() # Not required. Makes printing behave like a list. def __repr__(self): return self._list.__repr__() @abstractmethod def method1(): pass class Sub0(Super): pass class Sub1(Super): def __init__(self): self._list = [1, 2, 3] def method1(self): return [x**2 for x in self._list] def method2(self): return [x/2.0 for x in self._list] class Sub2(Super): def __init__(self): self._list = [10, 20, 30, 40] def method1(self): return [x+2 for x in self._list] We've added a new abstract method to Super, method1. This makes Super abstract again. A new class Sub0 which inherits from Super but does not implement method1, so it's also an ABC. Two new classes Sub1 and Sub2, which both inherit from Super. They both implement method1 from Super, so they're not abstract. Both implementations of method1 are different. Sub1 and Sub2 also both initialize themselves differently; in real life they might initialize themselves wildly differently. So you have two subclasses which both "is a" Super (they both implement Super's required interface) although their implementations are different. Also remember that Super, although an ABC, provides four non-abstract methods. So Super provides two things to subclasses: an implementation of collections.Sequence, and an additional abstract interface (the one abstract method) that subclasses must implement. Also, class Sub1 implements an additional method, method2, which is not part of Super's interface. Sub1 "is a" Super, but it also has additional capabilities. Test it: In [52]: a = Super() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Super with abstract methods method1 In [53]: a = Sub0() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Sub0 with abstract methods method1 In [54]: a = Sub1() In [55]: a Out[55]: [1, 2, 3] In [56]: b = Sub2() In [57]: b Out[57]: [10, 20, 30, 40] In [58]: print a, b [1, 2, 3] [10, 20, 30, 40] In [59]: a, b Out[59]: ([1, 2, 3], [10, 20, 30, 40]) In [60]: a.method1() Out[60]: [1, 4, 9] In [61]: b.method1() Out[61]: [12, 22, 32, 42] In [62]: a.method2() Out[62]: [0.5, 1.0, 1.5] [63]: a[:2] Out[63]: [1, 2] In [64]: a[0] = 5 --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: 'Sub1' object does not support item assignment Super and Sub0 are abstract and can't be instantiated (lines 52 and 53). Sub1 and Sub2 are concrete and have an immutable Sequence interface (54 through 59). Sub1 and Sub2 are instantiated differently, and their method1 implementations are different (60, 61). Sub1 includes an additional method2, beyond what's required by Super (62). Any concrete Super acts like a list/Sequence (63). A collections.Sequence is immutable (64). Finally, a wart: In [65]: a._list Out[65]: [1, 2, 3] In [66]: a._list = [] In [67]: a Out[67]: [] Super._list is spelled with a single underscore. Double underscore would have protected it from this last bit, but would have broken the implementation of methods in subclasses. Not sure why; I think because double underscore is private, and private means private. So ultimately this whole scheme relies on a gentleman's agreement not to reach in and muck with Super._list directly, as in line 65 above. Would love to know if there's a safer way to do that.

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  • Help with Boost Grammar

    - by Decmanc04
    I have been using the following win32 console code to try to parse a B Machine Grammar embedded within C++ using Boost Spirit grammar template. I am a relatively new Boost user. The code compiles, but when I run the .exe file produced by VC++2008, the program partially parses the input file. I believe the problem is with my grammar definition or the functions attached as semantic atctions. The code is given below: // BIFAnalyser.cpp : Defines the entry point for the console application. // // /*============================================================================= Copyright (c) Temitope Jos Onunkun 2010 http://www.dcs.kcl.ac.uk/pg/onun/ Use, modification and distribution is subject to the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) =============================================================================*/ //////////////////////////////////////////////////////////////////////////// // // // B Machine parser using the Boost "Grammar" and "Semantic Actions". // // // //////////////////////////////////////////////////////////////////////////// #include <boost/spirit/core.hpp> #include <boost/tokenizer.hpp> #include <iostream> #include <string> #include <fstream> #include <vector> #include <utility> /////////////////////////////////////////////////////////////////////////////////////////// using namespace std; using namespace boost::spirit; /////////////////////////////////////////////////////////////////////////////////////////// // // Semantic actions // //////////////////////////////////////////////////////////////////////////// vector<string> strVect; namespace { //semantic action function on individual lexeme void do_noint(char const* str, char const* end) { string s(str, end); if(atoi(str)) { ; } else { strVect.push_back(s); cout << "PUSH(" << s << ')' << endl; } } //semantic action function on addition of lexemes void do_add(char const*, char const*) { cout << "ADD" << endl; for(vector<string>::iterator vi = strVect.begin(); vi < strVect.end(); ++vi) cout << *vi << " "; } //semantic action function on subtraction of lexemes void do_subt(char const*, char const*) { cout << "SUBTRACT" << endl; for(vector<string>::iterator vi = strVect.begin(); vi < strVect.end(); ++vi) cout << *vi << " "; } //semantic action function on multiplication of lexemes void do_mult(char const*, char const*) { cout << "\nMULTIPLY" << endl; for(vector<string>::iterator vi = strVect.begin(); vi < strVect.end(); ++vi) cout << *vi << " "; cout << "\n"; } //semantic action function on division of lexemes void do_div(char const*, char const*) { cout << "\nDIVIDE" << endl; for(vector<string>::iterator vi = strVect.begin(); vi < strVect.end(); ++vi) cout << *vi << " "; } //semantic action function on simple substitution void do_sSubst(char const* str, char const* end) { string s(str, end); //use boost tokenizer to break down tokens typedef boost::tokenizer<boost::char_separator<char> > Tokenizer; boost::char_separator<char> sep("-+/*:=()"); // default char separator Tokenizer tok(s, sep); Tokenizer::iterator tok_iter = tok.begin(); pair<string, string > dependency; //create a pair object for dependencies //save first variable token in simple substitution dependency.first = *tok.begin(); //create a vector object to store all tokens vector<string> dx; // for( ; tok_iter != tok.end(); ++tok_iter) //save all tokens in vector { dx.push_back(*tok_iter ); } vector<string> d_hat; //stores set of dependency pairs string dep; //pairs variables as string object for(int unsigned i=1; i < dx.size()-1; i++) { dependency.second = dx.at(i); dep = dependency.first + "|->" + dependency.second + " "; d_hat.push_back(dep); } cout << "PUSH(" << s << ')' << endl; for(int unsigned i=0; i < d_hat.size(); i++) cout <<"\n...\n" << d_hat.at(i) << " "; cout << "\nSIMPLE SUBSTITUTION\n"; } //semantic action function on multiple substitution void do_mSubst(char const* str, char const* end) { string s(str, end); //use boost tokenizer to break down tokens typedef boost::tokenizer<boost::char_separator<char> > Tok; boost::char_separator<char> sep("-+/*:=()"); // default char separator Tok tok(s, sep); Tok::iterator tok_iter = tok.begin(); // string start = *tok.begin(); vector<string> mx; for( ; tok_iter != tok.end(); ++tok_iter) //save all tokens in vector { mx.push_back(*tok_iter ); } mx.push_back("END\n"); //add a marker "end" for(unsigned int i=0; i<mx.size(); i++) { // if(mx.at(i) == "END" || mx.at(i) == "||" ) // break; // else if( mx.at(i) == "||") // do_sSubst(str, end); // else // { // do_sSubst(str, end); // } cout << "\nTokens ... " << mx.at(i) << " "; } cout << "PUSH(" << s << ')' << endl; cout << "MULTIPLE SUBSTITUTION\n"; } } //////////////////////////////////////////////////////////////////////////// // // Simple Substitution Grammar // //////////////////////////////////////////////////////////////////////////// // Simple substitution grammar parser with integer values removed struct Substitution : public grammar<Substitution> { template <typename ScannerT> struct definition { definition(Substitution const& ) { multi_subst = (simple_subst [&do_mSubst] >> +( str_p("||") >> simple_subst [&do_mSubst]) ) ; simple_subst = (Identifier >> str_p(":=") >> expression)[&do_sSubst] ; Identifier = alpha_p >> +alnum_p//[do_noint] ; expression = term >> *( ('+' >> term)[&do_add] | ('-' >> term)[&do_subt] ) ; term = factor >> *( ('*' >> factor)[&do_mult] | ('/' >> factor)[&do_div] ) ; factor = lexeme_d[( (alpha_p >> +alnum_p) | +digit_p)[&do_noint]] | '(' >> expression >> ')' | ('+' >> factor) ; } rule<ScannerT> expression, term, factor, Identifier, simple_subst, multi_subst ; rule<ScannerT> const& start() const { return multi_subst; } }; }; //////////////////////////////////////////////////////////////////////////// // // Main program // //////////////////////////////////////////////////////////////////////////// int main() { cout << "************************************************************\n\n"; cout << "\t\t...Machine Parser...\n\n"; cout << "************************************************************\n\n"; // cout << "Type an expression...or [q or Q] to quit\n\n"; //prompt for file name to be input cout << "Please enter a filename...or [q or Q] to quit:\n\n "; char strFilename[256]; //file name store as a string object cin >> strFilename; ifstream inFile(strFilename); // opens file object for reading //output file for truncated machine (operations only) Substitution elementary_subst; // Simple substitution parser object string str, next; // inFile.open(strFilename); while (inFile >> str) { getline(cin, next); str += next; if (str.empty() || str[0] == 'q' || str[0] == 'Q') break; parse_info<> info = parse(str.c_str(), elementary_subst, space_p); if (info.full) { cout << "\n-------------------------\n"; cout << "Parsing succeeded\n"; cout << "\n-------------------------\n"; } else { cout << "\n-------------------------\n"; cout << "Parsing failed\n"; cout << "stopped at: \": " << info.stop << "\"\n"; cout << "\n-------------------------\n"; } } cout << "Please enter a filename...or [q or Q] to quit\n"; cin >> strFilename; return 0; } The contents of the file I tried to parse, which I named "mf7.txt" is given below: debt:=(LoanRequest+outstandingLoan1)*20 || newDebt := loanammount-paidammount The output when I execute the program is: ************************************************************ ...Machine Parser... ************************************************************ Please enter a filename...or [q or Q] to quit: c:\tplat\mf7.txt PUSH(LoanRequest) PUSH(outstandingLoan1) ADD LoanRequest outstandingLoan1 MULTIPLY LoanRequest outstandingLoan1 PUSH(debt:=(LoanRequest+outstandingLoan1)*20) ... debt|->LoanRequest ... debt|->outstandingLoan1 SIMPLE SUBSTITUTION Tokens ... debt Tokens ... LoanRequest Tokens ... outstandingLoan1 Tokens ... 20 Tokens ... END PUSH(debt:=(LoanRequest+outstandingLoan1)*20) MULTIPLE SUBSTITUTION ------------------------- Parsing failedstopped at: ": " ------------------------- My intention is to capture only the variables in the file, which I managed to do up to the "||" string. Clearly, the program is not parsing beyond the "||" string in the input file. I will appreciate assistance to fix the grammar. SOS, please.

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  • Networking issues with Linux server (CentOS 5.3)

    - by sxanness
    I have a Linux server hosting our bug tracking software (CentOS 5.2 Kernel 2.6.18-128.4.1.el5) that I have having some strange network problems with. The machine is configured with two NICS, one for the public interface and the other for our server back end network. The problem is that after doing a service network restart I can ping the public interface and it sends anywhere from 200-500 ICMP packets and then all of a sudden I start getting a request timed out error. Strange but as soon as I connect to the private interface the ping starts working again to the public interface. I clearly have a routing issue somewhere. I have a Juniper Router with the following configuration. Interface 0/0 -- Connect subnet to the ISP at our co-location Interface 0/2 -- For our DRAC network Interface 0/3 -- The Server-backend network (plugs directly into a switch that feeds to all the NICs that are on the 10.3.20.x network. Interface 0/4 -- Plugs directly into another switch that feeds our public interfaces, that interface as all the gateways from our public ip rangs as secondary IP addresses. I hope that someone can ask the right questions that can lead me to check things and figure out what is going on. Has anyone had similar problems and what kind of things should I be checking? Routing issue or something even more complicated? [root@fogbugz ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0 # Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ DEVICE=eth0 BOOTPROTO=static IPADDR=72.249.134.98 NETMASK=255.255.255.248 BROADCAST=72.249.134.103 HWADDR=00:16:3E:AA:BB:EE ONBOOT=yes [root@fogbugz ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1 # Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ DEVICE=eth1 BOOTPROTO=static BROADCAST=10.3.20.255 HWADDR=00:17:3E:AA:BB:EE IPADDR=10.3.20.25 NETMASK=255.255.255.0 NETWORK=10.3.20.0 ONBOOT=yes [root@fogbugz ~]# cat /etc/sysconfig/network NETWORKING=yes NETWORKING_IPV6=no HOSTNAME=fogbugz.dfw.hisg-it.net GATEWAY=72.249.134.97 [root@fogbugz ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 72.249.134.96 0.0.0.0 255.255.255.248 U 0 0 0 eth0 10.3.20.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1 10.0.0.0 10.3.20.1 255.0.0.0 UG 0 0 0 eth1 0.0.0.0 72.249.134.97 0.0.0.0 UG 0 0 0 eth0

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  • Networking issues with Linux server (CentOS 5.3)

    - by sxanness
    I have a Linux server hosting our bug tracking software (CentOS 5.2 Kernel 2.6.18-128.4.1.el5) that I have having some strange network problems with. The machine is configured with two NICS, one for the public interface and the other for our server back end network. The problem is that after doing a service network restart I can ping the public interface and it sends anywhere from 200-500 ICMP packets and then all of a sudden I start getting a request timed out error. Strange but as soon as I connect to the private interface the ping starts working again to the public interface. I clearly have a routing issue somewhere. I have a Juniper Router with the following configuration. Interface 0/0 -- Connect subnet to the ISP at our co-location Interface 0/2 -- For our DRAC network Interface 0/3 -- The Server-backend network (plugs directly into a switch that feeds to all the NICs that are on the 10.3.20.x network. Interface 0/4 -- Plugs directly into another switch that feeds our public interfaces, that interface as all the gateways from our public ip rangs as secondary IP addresses. I hope that someone can ask the right questions that can lead me to check things and figure out what is going on. Has anyone had similar problems and what kind of things should I be checking? Routing issue or something even more complicated? [root@fogbugz ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0 # Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ DEVICE=eth0 BOOTPROTO=static IPADDR=72.249.134.98 NETMASK=255.255.255.248 BROADCAST=72.249.134.103 HWADDR=00:16:3E:AA:BB:EE ONBOOT=yes [root@fogbugz ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1 # Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ DEVICE=eth1 BOOTPROTO=static BROADCAST=10.3.20.255 HWADDR=00:17:3E:AA:BB:EE IPADDR=10.3.20.25 NETMASK=255.255.255.0 NETWORK=10.3.20.0 ONBOOT=yes [root@fogbugz ~]# cat /etc/sysconfig/network NETWORKING=yes NETWORKING_IPV6=no HOSTNAME=fogbugz.dfw.hisg-it.net GATEWAY=72.249.134.97 [root@fogbugz ~]# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 72.249.134.96 0.0.0.0 255.255.255.248 U 0 0 0 eth0 10.3.20.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1 10.0.0.0 10.3.20.1 255.0.0.0 UG 0 0 0 eth1 0.0.0.0 72.249.134.97 0.0.0.0 UG 0 0 0 eth0

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  • Mac OS X Server Configure DHCP Options 66 and 67

    - by Paul Adams
    I need to configure Mountain Lion (10.8.2) OS X Server BOOTP to provide DHCP options 66 and 67 to provide PXE booting for PCs on my network. I have tried following the bootpd MAN pages, but they are not specific enough. I have also read conflicting information on the net, but nothing definitive for Mountain Lion DHCP. From bootpd man page: bootpd has a built-in type conversion table for many more options, mostly those specified in RFC 2132, and will try to convert from whatever type the option appears in the property list to the binary, packet format. For example, if bootpd knows that the type of the option is an IP address or list of IP addresses, it converts from the string form of the IP address to the binary, network byte order numeric value. If the type of the option is a numeric value, it converts from string, integer, or boolean, to the proper sized, network byte-order numeric value. Regardless of whether bootpd knows the type of the option or not, you can always specify the DHCP option using the data property list type <key>dhcp_option_128</key> <data> AAqV1Tzo </data> My TFTP server is 172.16.152.20 and the bootfile is pxelinux.0 I have edited /etc/bootpd.plist and added the following to the subnet dict: <key>dhcp_option_66</key> <data> LW4gLWUgrBCYFAo= </data> <key>dhcp_option_67</key> <data> LW4gLWUgcHhlbGludXguMAo= </data> According to the man page, the data elements are supposed to be Base64 encoded, but no matter what I try, I cannot get PXE clients to boot. I have tried encoding 172.16.152.20 using various methods: echo "172.16.152.20" | openssl enc -base64 returns MTcyLjE2LjE1Mi4yMAo= DHCP Option Code Utility (http://mac.softpedia.com/get/Internet-Utilities/DHCP-Option-Code-Utility.shtml) generating a string from 172.16.152.20 yields: LW4gLWUgMTcyLjE2LjE1Mi4yMAo= (used in the above example) DHCP Option Code Utility generating an IP Addresss from 172.16.152.20 yields: LW4gLWUgrBCYFAo= Encoding pxelinux.0 with the above methods likewise yields different encodings. I have tried using all three methods of encoding the data elements, but nothing seems to work i.e. my PXE boot clients do not get directed to my TFTP server. Can anyone help? Regards, Paul Adams.

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  • SSL connection errors from Apache

    - by Yang
    I'm running a (self-signed) SSL cert site on Apache/2.2.14 on Ubuntu 10.04, but various browsers are giving errors on half the connection attempts. Just now saw this transient error from Chrome: "Error 126 (net::ERR_SSL_BAD_RECORD_MAC_ALERT): Unknown error." Hit refresh and the problem goes away for a while. wget too: $ wget --no-check-certificate https://dev.foo.com/deps/ --2010-09-08 19:30:26-- https://dev.foo.com/deps/ Resolving dev.foo.com... 184.72.53.220 Connecting to dev.foo.com|184.72.53.220|:443... connected. OpenSSL: error:0407006A:rsa routines:RSA_padding_check_PKCS1_type_1:block type is not 01 OpenSSL: error:04067072:rsa routines:RSA_EAY_PUBLIC_DECRYPT:padding check failed OpenSSL: error:1408D07B:SSL routines:SSL3_GET_KEY_EXCHANGE:bad signature Unable to establish SSL connection. Run it right away again and it works: $ wget --no-check-certificate https://dev.foo.com/deps/ --2010-09-08 19:30:29-- https://dev.foo.com/deps/ Resolving dev.foo.com... 184.72.53.220 Connecting to dev.foo.com|184.72.53.220|:443... connected. WARNING: cannot verify dev.foo.com's certificate, issued by `/CN=dev.foo.com': Self-signed certificate encountered. HTTP request sent, awaiting response... 200 OK Length: 3157 (3.1K) [text/html] Saving to: `index.html' 100%[======================================>] 3,157 --.-K/s in 0s 2010-09-08 19:30:29 (48.6 MB/s) - `index.html' saved [3157/3157] In my sites-enabled/default-ssl: SSLCertificateFile /etc/ssl/certs/ssl-cert-snakeoil.pem SSLCertificateKeyFile /etc/ssl/private/ssl-cert-snakeoil.key The cert: -----BEGIN CERTIFICATE----- MIIBszCCARwCCQCa0TzNwqLgsTANBgkqhkiG9w0BAQUFADAeMRwwGgYDVQQDExNk ZXYucGFydHlvbmRhdGEuY29tMB4XDTEwMDgyNzA2MzA1N1oXDTIwMDgyNDA2MzA1 N1owHjEcMBoGA1UEAxMTZGV2LnBhcnR5b25kYXRhLmNvbTCBnzANBgkqhkiG9w0B AQEFAAOBjQAwgYkCgYEAzXDEULpCUqIc9hV/ESFapkckR2uoYINA81DvG2aQZ9Ot Q30OwX2ae2CC4bSzJEIVlahU8vjVrWpmpa28NEhQbqh4ywwbl1XDrEVYI6Gkfimf snJhOKyaVrEhlwutYtBjmsz3ZIqwymMPm/6smVcSS5dJIynlSmtltxX6ivPcO8UC AwEAATANBgkqhkiG9w0BAQUFAAOBgQBGxHVkpSSOnZjzuySRepjhAlV/yhe9Fx23 fh12WrjQMEi98B7JEuNSLXDWckUN7O6XRc3RzKmazcGHJqzhn0Ov6gAmAE2XjZ/x VW21xmaLwk+KgYKFJbJJaP3jMSpU7I3aa11wqAkR2Zd4Nkm9N0YXYIzcBdfztTVI Et8mEHBFdg== -----END CERTIFICATE----- The cert is in turn generated via: $ make-ssl-cert generate-default-snakeoil --force-overwrite Apache version. $ apache2 -V Server version: Apache/2.2.14 (Ubuntu) Server built: Apr 13 2010 20:22:19 Server's Module Magic Number: 20051115:23 Server loaded: APR 1.3.8, APR-Util 1.3.9 Compiled using: APR 1.3.8, APR-Util 1.3.9 Architecture: 64-bit Server MPM: Worker threaded: yes (fixed thread count) forked: yes (variable process count) Server compiled with.... -D APACHE_MPM_DIR="server/mpm/worker" -D APR_HAS_SENDFILE -D APR_HAS_MMAP -D APR_HAVE_IPV6 (IPv4-mapped addresses enabled) -D APR_USE_SYSVSEM_SERIALIZE -D APR_USE_PTHREAD_SERIALIZE -D SINGLE_LISTEN_UNSERIALIZED_ACCEPT -D APR_HAS_OTHER_CHILD -D AP_HAVE_RELIABLE_PIPED_LOGS -D DYNAMIC_MODULE_LIMIT=128 -D HTTPD_ROOT="" -D SUEXEC_BIN="/usr/lib/apache2/suexec" -D DEFAULT_PIDLOG="/var/run/apache2.pid" -D DEFAULT_SCOREBOARD="logs/apache_runtime_status" -D DEFAULT_ERRORLOG="logs/error_log" -D AP_TYPES_CONFIG_FILE="/etc/apache2/mime.types" -D SERVER_CONFIG_FILE="/etc/apache2/apache2.conf" I don't administer the network, hardware, etc. - this is all running on Amazon EC2. I'm not running a load-balancer or anything else in front of the server. I'm making direct TCP connections to that host (AFAIK). Any ideas? Thanks in advance for any help.

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