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• How do I Order on common attribute of two models in the DB?

  - by Will

  If i have two tables Books, CDs with corresponding models. I want to display to the user a list of books and CDs. I also want to be able to sort this list on common attributes (release date, genre, price, etc.). I also have basic filtering on the common attributes. The list will be large so I will be using pagination in manage the load. items = [] items << CD.all(:limit => 20, :page => params[:page], :order => "genre ASC") items << Book.all(:limit => 20, :page => params[:page], :order => "genre ASC") re_sort(items,"genre ASC") Right now I am doing two queries concatenating them and then sorting them. This is very inefficient. Also this breaks down when I use paging and filtering. If I am on page 2 of how do I know what page of each table individual table I am really on? There is no way to determine this information without getting all items from each table. I have though that if I create a new Class called items that has a one to one relationship with either a Book or CD and do something like Item.all(:limit => 20, :page => params[:page], :include => [:books, :cds], :order => "genre ASC") However this gives back an ambiguous error. So can only be refined as Item.all(:limit => 20, :page => params[:page], :include => [:books, :cds], :order => "books.genre ASC") And does not interleave the books and CDs in a way that I want. Any suggestions.

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• Can a lambda can be used to change a List's values in-place ( without creating a new list)?

  - by Saint Hill

  I am trying to determine the correct way of transforming all the values in a List using the new lambdas feature in the upcoming release of Java 8 without creating a **new** List. This pertains to times when a List is passed in by a caller and needs to have a function applied to change all the contents to a new value. For example, the way Collections.sort(list) changes a list in-place. What is the easiest way given this transforming function and this starting list: String function(String s){ return [some change made to value of s]; } List<String> list = Arrays.asList("Bob", "Steve", "Jim", "Arbby"); The usual way of applying a change to all the values in-place was this: for (int i = 0; i < list.size(); i++) { list.set(i, function( list.get(i) ); } Does lambdas and Java 8 offer: an easier and more expressive way? a way to do this without setting up all the scaffolding of the for(..) loop?

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• MySQL 5.5.8 Gets Periodic Lag

  - by CYREX

  Am using MySQL 5.5.8 on an Ubuntu system and every X amount of time it creates a huge lag that lasts a couple of seconds. Then all goes back to normal until the next lag. The time period varies but it looks like it happen periodically. Am using InnoDB. It is like hiccups in the MySQL. What could be creating this sort of periodic problem. Do not have any cron jobs or process running every time the X period happens. The X period could be between 30 minutes to 2 hours. So for example it could happen every 30 minutes for the next 12 hours or it could happen every 2 hours for the next 8 hours. key_buffer_size = 256M max_allowed_packet = 1M table_cache = 1024 table_open_cache = 1024 sort_buffer_size = 2M read_buffer_size = 2M read_rnd_buffer_size = 4M myisam_sort_buffer_size = 32M thread_cache_size = 128 query_cache_size= 128M log-slow-queries = slow.log long_query_time = 5 log-queries-not-using-indexes # Try number of CPU's*2 for thread_concurrency thread_concurrency = 4 max_connections=512 #innodb_data_file_path = ibdata1:10M:autoextend #innodb_log_group_home_dir = /usr/local/mysql/data # You can set .._buffer_pool_size up to 50 - 80 % # of RAM but beware of setting memory usage too high innodb_buffer_pool_size = 1G #innodb_additional_mem_pool_size = 20M # Set .._log_file_size to 25 % of buffer pool size #innodb_log_file_size = 64M #innodb_log_buffer_size = 8M #innodb_flush_log_at_trx_commit = 0 #innodb_lock_wait_timeout = 50 [mysqldump] quick max_allowed_packet = 16M [myisamchk] key_buffer_size = 64M sort_buffer_size = 64M read_buffer = 2M write_buffer = 2M There are about 200+ tables divided in 3 databases. The most written too is in InnoDB. The other ones are more read. Several of the tables in the InnoDB have more than 2 million records. The other databases top at about 400 thousand records and do not change so often. The PC is a Core 2 Duo 8400 with 4GB RAM, 32Bit Ubuntu.

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• The most efficient way to calculate an integral in a dataset range

  - by Annalisa

  I have an array of 10 rows by 20 columns. Each columns corresponds to a data set that cannot be fitted with any sort of continuous mathematical function (it's a series of numbers derived experimentally). I would like to calculate the integral of each column between row 4 and row 8, then store the obtained result in a new array (20 rows x 1 column). I have tried using different scipy.integrate modules (e.g. quad, trpz,...). The problem is that, from what I understand, scipy.integrate must be applied to functions, and I am not sure how to convert each column of my initial array into a function. As an alternative, I thought of calculating the average of each column between row 4 and row 8, then multiply this number by 4 (i.e. 8-4=4, the x-interval) and then store this into my final 20x1 array. The problem is...ehm...that I don't know how to calculate the average over a given range. The question I am asking are: Which method is more efficient/straightforward? Can integrals be calculated over a data set like the one that I have described? How do I calculate the average over a range of rows?

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• What are the javascript performance tradeoffs in adding id's to dom elements?

  - by Blinky

  For example, I have a website which has a dynamically-generated segment of its dom which looks roughly like this: <div id="master"> <div class="child"> ... </div> <div class="child"> ... </div> <div class="child"> ... </div> ... <div class="child"> ... </div> </div> There might be hundreds of child elements in this manner, and they, too, might have yet more children. At present, none of them have id's except for the master. Javascript manipulates them via dom-walking. It's a little scary. I'd like to add id's, e.g.: <div id="master"> <div id="child1" class="child"> ... </div> <div id="child2" class="child"> ... </div> <div id="child3" class="child"> ... </div> ... <div id="childN" class="child"> ... </div> </div> What are the tradeoffs in adding id's to these divs? Certainly, jQuery must maintain a hash of id's, so there's going to be some sort of performance hit. Any general guidelines in when adding additional id's is a bad idea? Is jQuery so awesome that, in practice, it doesn't matter?

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• How can I get my business objects layer to use the management layer in their methods?

  - by Tom Pickles

  I have a solution in VS2010 with several projects, each making up a layer within my application. I have business entities which are currently objects with no methods, and I have a management layer which references the business entities layer in it's project. I now think I have designed my application poorly and would like to move methods from helper classes (which are in another layer) into methods I'll create within the business entities themselves. For example I have a VirtualMachine object, which uses a helper class to call a Reboot() method on it which passes the request to the management layer. The static manager class talks to an API that reboots the VM. I want to move the Reboot() method into the VirtualMachine object, but I will need to reference the management layer: public void Reboot() { VMManager.Reboot(this.Name); } So if I add a reference to my management project in my entities project, I get the circular dependency error, which is how it should be. How can I sort this situation out? Do I need to an yet another layer between the entity layer and the management layer? Or, should I just forget it and leave it as it is. The application works ok now, but I am concerned my design isn't particularly OOP centric and I would like to correct this.

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• fopen() fails to open stream: permission denied, yet permissions should be valid

  - by about blank

  So, I have this error: Warning: fopen(/path/to/test-in.txt) [function.fopen]: failed to open stream: Permission denied Performing ls -l in the directory where test-in.txt is produces the following output: -rw-r--r-- 1 $USER $USER 1921 Sep 6 20:09 test-in.txt -rw-r--r-- 1 $USER $USER 0 Sep 6 20:08 test-out.txt In order to get past this, I decided to perform the following: chgrp -R www-data /path/to/php/webroot And then did: chmod g+rw /path/to/php/webroot Yet, I still get this error when I run my php5 script to open the file. Why is this happening? I've tried this using LAMP as well as cherokee through CGI, so it can't be this. Is there a solution of some sort? Edit I'll also add that I'm just developing via localhost right now. Update - PHP fopen() line $fullpath = $this->fileRoot . $this->fileInData['fileName']; $file_ptr = fopen( $fullpath, 'r+' ); I should also mention I'd like to stick with Cherokee if possible. What's this deal about setting file permissions for Apache/Cherokee?

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• Strongly typed dynamic Linq sorting

  - by David

  I'm trying to build some code for dynamically sorting a Linq IQueryable<. The obvious way is here, which sorts a list using a string for the field name http://dvanderboom.wordpress.com/2008/12/19/dynamically-composing-linq-orderby-clauses/ However I want one change - compile time checking of field names, and the ability to use refactoring/Find All References to support later maintenance. That means I want to define the fields as f=f.Name, instead of as strings. For my specific use I want to encapsulate some code that would decide which of a list of named "OrderBy" expressions should be used based on user input, without writing different code every time. Here is the gist of what I've written: var list = from m Movies select m; // Get our list var sorter = list.GetSorter(...); // Pass in some global user settings object sorter.AddSort("NAME", m=m.Name); sorter.AddSort("YEAR", m=m.Year).ThenBy(m=m.Year); list = sorter.GetSortedList(); ... public class Sorter ... public static Sorter GetSorter(this IQueryable source, ...) The GetSortedList function determines which of the named sorts to use, which results in a List object, where each FieldData contains the MethodInfo and Type values of the fields passed in AddSort: public SorterItem AddSort(Func field) { MethodInfo ... = field.Method; Type ... = TypeOf(TKey); // Create item, add item to diction, add fields to item's List // The item has the ThenBy method, which just adds another field to the List } I'm not sure if there is a way to store the entire field object in a way that would allow it be returned later (it would be impossible to cast, since it is a generic type) Is there a way I could adapt the sample code, or come up with entirely new code, in order to sort using strongly typed field names after they have been stored in some container and retrieved (losing any generic type casting)

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• How do you tell that your unit tests are correct?

  - by Jacob Adams

  I've only done minor unit testing at various points in my career. Whenever I start diving into it again, it always troubles me how to prove that my tests are correct. How can I tell that there isn't a bug in my unit test? Usually I end up running the app, proving it works, then using the unit test as a sort of regression test. What is the recommended approach and/or what is the approach you take to this problem? Edit: I also realize that you could write small, granular unit tests that would be easy to understand. However, if you assume that small, granular code is flawless and bulletproof, you could just write small, granular programs and not need unit testing. Edit2: For the arguments "unit testing is for making sure your changes don't break anything" and "this will only happen if the test has the exact same flaw as the code", what if the test overfits? It's possible to pass both good and bad code with a bad test. My main question is what good is unit testing since if your tests can be flawed you can't really improve your confidence in your code, can't really prove your refactoring worked, and can't really prove that you met the specification?

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• .NET MVC: How to fix Visual Studio's lack of awareness of CSS classes in partial views?

  - by Mega Matt

  Hi all, This has been sort of an annoyance for me for a while. I make pretty heavy use of partial views in MVC, and am using Visual Studio 2008 to develop. The problem is that when I give html elements a class in a partial view (<div class="someClass">), it will underline them in green like it doesn't know what they are. I realize this is because I'm in a partial view, and haven't put link tags anywhere in that file for it to know where the CSS is (the link tags are in the main view that renders the partial view). The CSS still works fine on my site because the browser will render all views as one long html page anyway, but it's really annoying to look through my partial views and see all of my classes underlined in green. Is there a way that I can still tell Visual Studio that those classes exist somewhere, from the partial view? I figured there has to be a way to let it know, but am not sure what it is. Maybe a way to import the stylesheets from the parent view? Thanks for your help.

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• Ajax and JSF 1.1 using hidden iframe with "proxy forms", what do you think about this development st

  - by Steel Plume

  Hi, currently I am using yet 1.1 specs, so I am trying to make simple what is too complex for me :p, managing backing beans with conflicting navigation rules, external params breaking rules and so on... for example when I need a backing bean used by other "views" simply I call it using FacesContext inside other backing beans, but often it's too wired up to JSF navigation/initialization rules to be really usable, and of course more simple is more useful become the FacesContext. So with only a bit of cross browser Javascript (simply a form copy and a read-write on a "proxy" form), I create a sort of proxy form inside the main user page (totally disassociated from JSF navigation rules, but using JSF taglibs). Ajax gives me flexibility on the user interaction, but data is always managed by JSF. Pratically I demand all "fictious" user actions to an hidden "iframe" which build up all needed forms according JSF rules, then a javascript simply clone its form output and put it into the user view level (CSS for showing/hiding real command buttons and making pretty), the user plays around and when he click submit, a script copies all "proxied" form values into the real JSF form inside the "iframe" that invokes the real submit of the form, what it returns is obviously dependent by your choice. Now JSF is really a pleasure :-p My real interest is to know what are your alternative strategy for using pure Ajax and JSF 1.1 without adopting middle layer like ajax4jsf and others, all good choices but too much "plugins" than specs.

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• Weird problem with PHP mail() under Linux.

  - by Vilx-

  This is the case when it "works on my machine". Except that my machine is Windows, and the target is some sort of Linux. The idea is that the mail() function puts a newline between the MIME-Version and Content-Type headers, thus breaking the whole thing. Here's the code, simpliefied as much as possible: <?php $HTMLPart = chunk_split(base64_encode('<html><body style="color: red">Test.</body></html>')); $PlaintextPart = chunk_split(base64_encode('>>> TEST <<<')); $Headers =<<<AKAM From: "My Test" <[email protected]> Reply-To: [email protected] MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="9-1410065408-1410065408=:27514" AKAM; $Body =<<<AKAM This is a multi-part message in MIME format. --9-1410065408-1410065408=:27514 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: base64 $PlaintextPart --9-1410065408-1410065408=:27514 Content-Type: text/html; charset="windows-1252" Content-Transfer-Encoding: base64 $HTMLPart --9-1410065408-1410065408=:27514-- AKAM; echo 'Try 3: '; echo mail('[email protected]', 'Testmail', $Body, $Headers) ? 'WIN' : 'FAIL'; ?>

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• Ensuring quality of your software and code

  - by Filip Ekberg

  When I usually write code I follow some guidelines to ensure that my code has a certain standard and I as any other developer try to ensure that my code and software is of quality. Try to focus on the programming and not the understanding of the domain or any other pre-programming steps. These are the following steps I live by: Writing unit tests Make it fail ( no code ) Make it Work ( working code ) Analysing abstraction Extracting methods Exteract interfaces Refactoring In addition to the above which is a part of refactoring, I also try to refactor the code with good tools such as ReSharper, CodeRush or others. The question; What is the next step? Commenting the code is trivial and shouldn't even have to be mentioned, but updated comments and xml-comments where it's needed / everywhere is something that I try to have. But all the above helps he ensure that other developers might understand my code, that the code has some sort of quality and follows naming standards. It does however not ensure any product quality. I am looking for tools for post-development quality ensurance, such as profilers and how one would use these tools to increase product quality.

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• C# Changing Objects within a List

  - by kwong22

  Hi, I'm having a little problem changing members of an object in a list using a found index. So this is the method I am currently working with: static void addToInventory(ref List<baseItem> myArray, baseItem item, float maxAmount, ref float currentAmount) { if (currentAmount + item.getWeight() <= maxAmount) { Console.WriteLine("item.Quantity = {0}", item.Quantity); if (myArray.Contains(item)) { Console.WriteLine("Item ({0}) already exists", item.Name); int id = myArray.IndexOf(item); myArray[id].Quantity += item.Quantity;//Change occurs in this line, item.Quantity becomes the same as myArray[id].Quantity } else { Console.WriteLine("Adding new item ({0})", item.Name); myArray.Add(item); } currentAmount += item.getWeight(); } else { Console.WriteLine("Inventory full"); } myArray.Sort(); } This method takes several parameters including the inventory/list. I check if the item fits in and if it does, I see if there is another item of the same name in the list, find the index, and add more of the item. However, the quantity of the item added suddenly becomes the same as the quantity of the item in the list. For some reason, this also changes the quantity of the item outside of the list. So therefore, instead of quantities adding up like this: 1, 2, 3, 4, they add up like this: 1, 2, 4, 8. I've just started to learn how to use lists so if there is anything I'm missing, don't hesitate to criticize. Thanks in advance.

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• Matching innermost braces with regex or strpos?

  - by rich97

  I have a sort of mini parsing syntax I made up to help me streamline my view code in cakephp. Basically I have created a table helper which, when given a dataset and (optionally) a set of options for how to format the data will render out a table, as opposed to me looping though the data and editing it manually. It allows the user to be as complex or as simple as they like, it can get pretty powerful. However, In order to achieve this I had to make a simple parsing syntax. As a quick example the user would do something like so: $this->Table->data = $userData; $this->Table->elements['td']['data'] = array( '{:User.username:}', '{:User.created:}' => array('Time::nice') ); echo $this->Table->render(); And when rendering the table would then generate: <table> <tbody> <tr><td>rich97</td><td>Sun 21st 02:30pm</td></tr> </tbody> </table> The problem occurs then I try to nest the braces like so: {:User.levels.iconClasses.{:User.access:}:} Is there anyway I can only get the inner most brackets on the first time round and loop though until there are no matches? Or even do it in one go? Or even better use strpos? Here is my regex as it stands: '/\{\:([^}]+)\:\}/'

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• Conditional deserialization

  - by Yordan Pavlov

  I am still not sure whether the title of my question is correct and it most probably is not. However I have spent some time searching both the net and stackoverflow and I can not find a good description of the issue I am facing. Basically what I want to achieve is the ability to read some raw bytes and based on the value of some of them to interpret the rest in different ways. This is how TLV works in a way, you check the tag and depending on it - interpret the result. Of course I can always keep that logic in my C++ code, however I am looking for a solution which would move the logic out of the source code (maybe to some xml description). This would allow me to describe different encodings (protocols) more easily. I am familiar with Protocol Buffers and some other serialization libraries, however all of them solve different issue. They assume they are on both ends of the communication, while I want to describe the communication (sort of). Is such solution available, if no - why not? Are there some inherent difficulties I will face trying to implement it.

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• Please help with C++ syntax for const accessor by reference.

  - by Hamish Grubijan

  Right not my implementation returns the thing by value. The member m_MyObj itself is not const - it's value changes depending on what the user selects with a Combo Box. I am no C++ guru, but I want to do this right. If I simply stick a & in front of GetChosenSourceSystem in both decl. and impl., I get one sort of compiler error. If I do one but not another - another error. If I do return &m_MyObj;. I will not list the errors here for now, unless there is a strong demand for it. I assume that an experienced C++ coder can tell what is going on here. I could omit constness or reference, but I want to make it tight and learn in the process as well. Thanks! // In header file MyObj GetChosenThingy() const; // In Implementation file. MyObj MyDlg::GetChosenThingy() const { return m_MyObj; }

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• Starting a code library.

  - by Rob Stevenson-Leggett

  Hi, I've been meaning to start a library of reusable code snippets for a while and never seem to get round to it. I think my main problems are: Where to start. What structure should my library take? Should it be a compiled library (where appropriate or just classes I can drop into any project? Or a library project that can be included? In my experience, a built library will quickly become out of date and the source will get lost. So I'm leaning towards source libraries that I can export from SVN and include in any project. Intellectual property. I am employeed, so a lot of the code I write is not my IP. How can I ensure that I don't give my own IP away using it on projects in work and at home? I'm thinking the best way would be to licence my library with an open source licence and make sure I only add to it in my own time using my own equipment and therefore making sure that if I use it in a work project the same rules apply as if I was using a third party library. I write in many different languages and often would require two or more parts of this library. Should I look at implementing a few template projects and a core project for each of my chosen reusable components and languages? Has anyone else got this sort of library and how do you organise and update it?

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• Is Assert.Fail() considered bad practice?

  - by Mendelt

  I use Assert.Fail a lot when doing TDD. I'm usually working on one test at a time but when I get ideas for things I want to implement later I quickly write an empty test where the name of the test method indicates what I want to implement as sort of a todo-list. To make sure I don't forget I put an Assert.Fail() in the body. When trying out xUnit.Net I found they hadn't implemented Assert.Fail. Of course you can always Assert.IsTrue(false) but this doesn't communicate my intention as well. I got the impression Assert.Fail wasn't implemented on purpose. Is this considered bad practice? If so why? @Martin Meredith That's not exactly what I do. I do write a test first and then implement code to make it work. Usually I think of several tests at once. Or I think about a test to write when I'm working on something else. That's when I write an empty failing test to remember. By the time I get to writing the test I neatly work test-first. @Jimmeh That looks like a good idea. Ignored tests don't fail but they still show up in a separate list. Have to try that out. @Matt Howells Great Idea. NotImplementedException communicates intention better than assert.Fail() in this case @Mitch Wheat That's what I was looking for. It seems it was left out to prevent it being abused in another way I abuse it.

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• How not to lose binding source updates?

  - by Fyodor Soikin

  Suppose I have a modal dialog with a textbox and OK/Cancel buttons. And it is built on MVVM - i.e. it has a ViewModel object with a string property that the textbox is bound to. Say, I enter some text in the textbox and then grab my mouse and click "OK". Everything works fine: at the moment of click, the textbox loses focus, which causes the binding engine to update the ViewModel's property. I get my data, everybody's happy. Now suppose I don't use my mouse. Instead, I just hit Enter on the keyboard. This also causes the "OK" button to "click", since it is marked as IsDefault="True". But guess what? The textbox doesn not lose focus in this case, and therefore, the binding engine remains innocently ignorant, and I don't get my data. Dang! Another variation of the same scenario: suppose I have a data entry form right in the main window, enter some data into it, and then hit Ctrl+S for "Save". Guess what? My latest entry doesn't get saved! This may be somewhat remedied by using UpdateSourceTrigger=PropertyChanged, but that is not always possible. One obvious case would be the use of StringFormat with binding - the text keeps jumping back into "formatted" state as I'm trying to enter it. And another case, which I have encountered myself, is when I have some time-consuming processing in the viewmodel's property setter, and I only want to perform it when the user is "done" entering text. This seems like an eternal problem: I remember trying to solve it systematically from ages ago, ever since I've started working with interactive interfaces, but I've never quite succeeded. In the past, I always ended up using some sort of hacks - like, say, adding an "EnsureDataSaved" method to every "presenter" (as in "MVP") and calling it at "critical" points, or something like that... But with all the cool technologies, as well as empty hype, of WPF, I expected they'd come up with some good solution.

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• Converting Source ASCII Files to JPEGs

  - by CommonsWare

  I publish technical books, in print, PDF, and Kindle/MOBI, with EPUB on the way. The Kindle does not support monospace fonts, which are kinda useful for source code listings. The only way to do monospace fonts is to convert the text (Java source, HTML, XML, etc.) into JPEG images. More specifically, due to pagination issues, a given input ASCII file needs to be split into slices of ~6 lines each, with each slice turned into a JPEG, so listings can span a screen. This is a royal pain. My current mechanism to do that involves: Running expand to set a consistent 2-space tab size, which pipes to... a2ps, which pipes to... A small Perl snippet to add a "%%LanguageLevel: 3\n" line, which pipes to... ImageMagick's convert, to take the (E)PS and make a JPEG out it, with an appropriate background, cropped to 575x148+5+28, etc. That used to work 100% of the time. It now works 95% of the time. The rest of the time, I get convert: geometry does not contain image errors, which I cannot seem to get rid of, in part because I don't understand what the problem is. Before this process, I used to use a pretty-print engine (source-highlight) to get HTML out of the source code...but then the only thing I could find to convert the HTML into JPEGs was to automate screen-grabs from an embedded Gecko engine. Reliability stank, which is why I switched to my current mechanism. So, if you were you, and you needed to turn source listings into JPEG images, in an automated fashion, how would you do it? Bonus points if it offers some sort of pretty-print process (e.g., bolded keywords)! Or, if you know what typically causes convert: geometry does not contain image, that might help. My current process is ugly, but if I could get it back to 100% reliability, that'd be just fine for now. Thanks in advance!

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• Appropriate uses of Monad `fail` vs. MonadPlus `mzero`

  - by jberryman

  This is a question that has come up several times for me in the design code, especially libraries. There seems to be some interest in it so I thought it might make a good community wiki. The fail method in Monad is considered by some to be a wart; a somewhat arbitrary addition to the class that does not come from the original category theory. But of course in the current state of things, many Monad types have logical and useful fail instances. The MonadPlus class is a sub-class of Monad that provides an mzero method which logically encapsulates the idea of failure in a monad. So a library designer who wants to write some monadic code that does some sort of failure handling can choose to make his code use the fail method in Monad or restrict his code to the MonadPlus class, just so that he can feel good about using mzero, even though he doesn't care about the monoidal combining mplus operation at all. Some discussions on this subject are in this wiki page about proposals to reform the MonadPlus class. So I guess I have one specific question: What monad instances, if any, have a natural fail method, but cannot be instances of MonadPlus because they have no logical implementation for mplus? But I'm mostly interested in a discussion about this subject. Thanks! EDIT: One final thought occured to me. I recently learned (even though it's right there in the docs for fail) that monadic "do" notation is desugared in such a way that pattern match failures, as in (x:xs) <- return [] call the monad's fail. It seems like the language designers must have been strongly influenced by the prospect of some automatic failure handling built in to haskell's syntax in their inclusion of fail in Monad.

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• Generate regular expression to match strings from the list A, but not from list B

  - by Vlad

  I have two lists of strings ListA and ListB. I need to generate a regular expression that will match all strings in ListA and will not match any string in ListB. The strings could contain any combination of characters, numbers and punctuation. If a string appears on ListA it is guaranteed that it will not be in the ListB. If a string is not in either of these two lists I don't care what the result of the matching should be. The lists typically contain thousands of strings, and strings are fairly similar to each other. I know the trivial answer to this question, which is just generate a regular expression of the form (Str1)|(Str2)|(Str3) where StrN is the string from ListA. But I am looking for a more efficient way to do this. Ideal solution would be some sort of tool that will take two lists and generate a Java regular expression for this. Update 1: By "efficient", I mean to generate expression that is shorter than trivial solution. The ideal algorithm would generate the shorted possible expression. Here are some examples. ListA = { C10 , C15, C195 } ListB = { Bob, Billy } The ideal expression would be /^C1.+$/ Another example, note the third element of ListB ListA = { C10 , C15, C195 } ListB = { Bob, Billy, C25 } The ideal expression is /^C[^2]{1}.+$/ The last example ListA = { A , D ,E , F , H } ListB = { B , C , G , I } The ideal expression is the same as trivial solution which is /^(A|D|E|F|H)$/ Also, I am not looking for the ideal solution, anything better than trivial would help. I was thinking along the lines of generating the list of trivial solutions, and then try to merge the common substrings while watching that we don't wander into ListB territory. *Update 2: I am not particularly worried about the time it takes to generate the RegEx, anything under 10 minutes on the modern machine is acceptable

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• Core Data object into an NSDictionary with possible nil objects

  - by Chuck

  I have a core data object that has a bunch of optional values. I'm pushing a table view controller and passing it a reference to the object so I can display its contents in a table view. Because I want the table view displayed a specific way, I am storing the values from the core data object into an array of dictionaries then using the array to populate the table view. This works great, and I got editing and saving working properly. (i'm not using a fetched results controller because I don't have anything to sort on) The issue with my current code is that if one of the items in the object is missing, then I end up trying to put nil into the dictionary, which won't work. I'm looking for a clean way to handle this, I could do the following, but I can't help but feeling like there's a better way. *passedEntry is the core data object handed to the view controller when it is pushed, lets say it contains firstName, lastName, and age, all optional. if ([passedEntry firstName] != nil) { [dictionary setObject:[passedEntry firstName] forKey:@"firstName"] } else { [dictionary setObject:@"" forKey:@"firstName"] } And so on. This works, but it feels kludgy, especially if I end up adding more items to the core data object down the road.

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• Move SELECT to SQL Server side

  - by noober

  Hello all, I have an SQLCLR trigger. It contains a large and messy SELECT inside, with parts like: (CASE WHEN EXISTS(SELECT * FROM INSERTED I WHERE I.ID = R.ID) THEN '1' ELSE '0' END) AS IsUpdated -- Is selected row just added? as well as JOINs etc. I like to have the result as a single table with all included. Question 1. Can I move this SELECT to SQL Server side? If yes, how to do this? Saying "move", I mean to create a stored procedure or something else that can be executed before reading dataset in while cycle. The 2 following questions make sense only if answer is "yes". Why do I want to move SELECT? First off, I don't like mixing SQL with C# code. At second, I suppose that server-side queries run faster, since the server have more chances to cache them. Question 2. Am I right? Is it some sort of optimizing? Also, the SELECT contains constant strings, but they are localizable. For instance, WHERE R.Status = "Enabled" "Enabled" should be changed for French, German etc. So, I want to write 2 static methods -- OnCreate and OnDestroy -- then mark them as stored procedures. When registering/unregistering my assembly on server side, just call them respectively. In OnCreate format the SELECT string, replacing {0}, {1}... with required values from the assembly resources. Then I can localize resources only, not every script. Question 3. Is it good idea? Is there an existing attribute to mark methods to be executed by SQL Server automatically after (un)registartion an assembly? Regards,

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