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  • I need to implement C# deep copy constructors with inheritance. What patterns are there to choose fr

    - by Tony Lambert
    I wish to implement a deepcopy of my classes hierarchy in C# public Class ParentObj : ICloneable { protected int myA; public virtual Object Clone () { ParentObj newObj = new ParentObj(); newObj.myA = theObj.MyA; return newObj; } } public Class ChildObj : ParentObj { protected int myB; public override Object Clone ( ) { Parent newObj = this.base.Clone(); newObj.myB = theObj.MyB; return newObj; } } This will not work as when Cloning the Child only a parent is new-ed. In my code some classes have large hierarchies. What is the recommended way of doing this? Cloning everything at each level without calling the base class seems wrong? There must be some neat solutions to this problem, what are they? Can I thank everyone for their answers. It was really interesting to see some of the approaches. I think it would be good if someone gave an example of a reflection answer for completeness. +1 awaiting!

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  • Modifying NSMutableDictionary from a single index format into nested (array within array)

    - by Michael Robinson
    I need to take the member ID off the top of this and create an array inside that contains the rest of the JSON return. Here is my JSON return. [{"F_Name_VC":"Frank", "L_Name_VC":"Johnson", "userid":"18", "age":"23", },] After it is json-deserialized it looks like this: I need convert it to be transformed into this, with children sub-array: Someone else posted a similar question but without the fact that it was coming from a JSON deserialization. There were two answers but no conclusion to the question. (Answer 1): NSDictionary *item1 = [NSDictionary dictionaryWithObjects:[NSArray arrayWithObjects:@" member",[NSNumber numberWithInt:3],nil] forKeys:[NSArray arrayWithObjects:@"Title",@"View",nil]]; Answer (2): NSMutableArray *Rows = [NSMutableArray arrayWithCapacity: 1]; for (int i = 0; i < 4; ++i) { NSMutableArray *theChildren = [NSMutableArray arrayWithCapacity: 1]; [theChildren addObject: [NSString stringWithFormat: @"tester %d", i]]; NSString *aTitle = [NSString stringWithFormat: @"Item %d", i]; NSDictionary *anItem = [NSDictionary dictionaryWithObjectsAndKeys: aTitle, @"Title", theChildren, @"Children"]; [Rows addObject: anItem]; } NSDictionary *Root = [NSDictionary withObject: Rows andKey: @"Rows"]; Here is my JSON return and save code: NSData *jsonData = [jsonreturn dataUsingEncoding:NSUTF32BigEndianStringEncoding]; NSError *error = nil; NSDictionary * dict = [[CJSONDeserializer deserializer] deserializeAsDictionary:jsonData error:&error]; if (dict) { rowsArray = [dict objectForKey:@"member"]; [rowsArray retain]; } Thanks in advance. Every tutorial on JSON only shows a simple array being returned, never with children..It's driving me crazy trying to figure this out.

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  • How can I make this method more Scalalicious

    - by Neil Chambers
    I have a function that calculates the left and right node values for some collection of treeNodes given a simple node.id, node.parentId association. It's very simple and works well enough...but, well, I am wondering if there is a more idiomatic approach. Specifically is there a way to track the left/right values without using some externally tracked value but still keep the tasty recursion. /* * A tree node */ case class TreeNode(val id:String, val parentId: String){ var left: Int = 0 var right: Int = 0 } /* * a method to compute the left/right node values */ def walktree(node: TreeNode) = { /* * increment state for the inner function */ var c = 0 /* * A method to set the increment state */ def increment = { c+=1; c } // poo /* * the tasty inner method * treeNodes is a List[TreeNode] */ def walk(node: TreeNode): Unit = { node.left = increment /* * recurse on all direct descendants */ treeNodes filter( _.parentId == node.id) foreach (walk(_)) node.right = increment } walk(node) } walktree(someRootNode) Edit - The list of nodes is taken from a database. Pulling the nodes into a proper tree would take too much time. I am pulling a flat list into memory and all I have is an association via node id's as pertains to parents and children. Adding left/right node values allows me to get a snapshop of all children (and childrens children) with a single SQL query. The calculation needs to run very quickly in order to maintain data integrity should parent-child associations change (which they do very frequently). In addition to using the awesome Scala collections I've also boosted speed by using parallel processing for some pre/post filtering on the tree nodes. I wanted to find a more idiomatic way of tracking the left/right node values. After looking at the answers listed I have settled on this synthesised version: def walktree(node: TreeNode) = { def walk(node: TreeNode, counter: Int): Int = { node.left = counter node.right = treeNodes .filter( _.parentId == node.id) .foldLeft(counter+1) { (counter, curnode) => walk(curnode, counter) + 1 } node.right } walk(node,1) }

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  • How to restrain one's self from the overwhelming urge to rewrite everything?

    - by Scott Saad
    Setup Have you ever had the experience of going into a piece of code to make a seemingly simple change and then realizing that you've just stepped into a wasteland that deserves some serious attention? This usually gets followed up with an official FREAK OUT moment, where the overwhelming feeling of rewriting everything in sight starts to creep up. It's important to note that this bad code does not necessarily come from others as it may indeed be something we've written or contributed to in the past. Problem It's obvious that there is some serious code rot, horrible architecture, etc. that needs to be dealt with. The real problem, as it relates to this question, is that it's not the right time to rewrite the code. There could be many reasons for this: Currently in the middle of a release cycle, therefore any changes should be minimal. It's 2:00 AM in the morning, and the brain is starting to shut down. It could have seemingly adverse affects on the schedule. The rabbit hole could go much deeper than our eyes are able to see at this time. etc... Question So how should we balance the duty of continuously improving the code, while also being a responsible developer? How do we refrain from contributing to the broken window theory, while also being aware of actions and the potential recklessness they may cause? Update Great answers! For the most part, there seems to be two schools of thought: Don't resist the urge as it's a good one to have. Don't give in to the temptation as it will burn you to the ground. It would be interesting to know if more people feel any balance exists.

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  • How to TDD Asynchronous Events?

    - by Padu Merloti
    The fundamental question is how do I create a unit test that needs to call a method, wait for an event to happen on the tested class and then call another method (the one that we actually want to test)? Here's the scenario if you have time to read further: I'm developing an application that has to control a piece of hardware. In order to avoid dependency from hardware availability, when I create my object I specify that we are running in test mode. When that happens, the class that is being tested creates the appropriate driver hierarchy (in this case a thin mock layer of hardware drivers). Imagine that the class in question is an Elevator and I want to test the method that gives me the floor number that the elevator is. Here is how my fictitious test looks like right now: [TestMethod] public void TestGetCurrentFloor() { var elevator = new Elevator(Elevator.Environment.Offline); elevator.ElevatorArrivedOnFloor += TestElevatorArrived; elevator.GoToFloor(5); //Here's where I'm getting lost... I could block //until TestElevatorArrived gives me a signal, but //I'm not sure it's the best way int floor = elevator.GetCurrentFloor(); Assert.AreEqual(floor, 5); } Edit: Thanks for all the answers. This is how I ended up implementing it: [TestMethod] public void TestGetCurrentFloor() { var elevator = new Elevator(Elevator.Environment.Offline); elevator.ElevatorArrivedOnFloor += (s, e) => { Monitor.Pulse(this); }; lock (this) { elevator.GoToFloor(5); if (!Monitor.Wait(this, Timeout)) Assert.Fail("Elevator did not reach destination in time"); int floor = elevator.GetCurrentFloor(); Assert.AreEqual(floor, 5); } }

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  • How to access SQL CE 3.5 from VB6

    - by Masterfu
    We have a .NET 3.5 SP1 application written in C# that stores data in an SQL CE 3.5 Database. We also need to access (read only) this very data from a legacy VB6 application. I don't know if this is at all possible. There are several approaches to this problem that I can think of. 1) I have read about ADOCE Connections, but this seems to be an option for embedded Visual Basic only 2) I can't seem to get a connection working using ADODB.Connection Objects like so Dim MyConnObj As New ADODB.Connection ' Microsoft.SQLSERVER.CE.OLEDB.3.5 ' Microsoft.SQLSERVER.MOBILE.OLEDB.3.0 MyConnObj.ConnectionString = "Provider=SQLOLEDB;Data Source=c:\test.sdf" MyConnObj.Open Maybe this is just a bad choice of providers? I also tried the providers that appear as comments above and different connection strings, but to no avail. Both providers are not installed on my dev machine and won't be installed on my customer's machine. 3) Maybe there is a way to use a more generic approach like ODBC? But I believe this would result in setup / deployment work, right? Does anyone have any experience with this scenario? As you can see, I am really looking for some good starting points. I also accept answers like "This is drop dead simple and so are you" as long as they come with some guiding directions ;-)

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  • How do you read a file line by line in your language of choice?

    - by Jon Ericson
    I got inspired to try out Haskell again based on a recent answer. My big block is that reading a file line by line (a task made simple in languages such as Perl) seems complicated in a functional language. How do you read a file line by line in your favorite language? So that we are comparing apples to other types of apples, please write a program that numbers the lines of the input file. So if your input is: Line the first. Next line. End of communication. The output would look like: 1 Line the first. 2 Next line. 3 End of communication. I will post my Haskell program as an example. Ken commented that this question does not specify how errors should be handled. I'm not overly concerned about it because: Most answers did the obvious thing and read from stdin and wrote to stdout. The nice thing is that it puts the onus on the user to redirect those streams the way they want. So if stdin is redirected from a non-existent file, the shell will take care of reporting the error, for instance. The question is more aimed at how a language does IO than how it handles exceptions. But if necessary error handling is missing in an answer, feel free to either edit the code to fix it or make a note in the comments.

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  • Stop Excel from changing cell contents, ever

    - by Enable Manual-Correct
    I work with card numbers, like credit card and ID numbers. We do not do any calculations with card numbers, obviously. They are "text." I format them as text, I type them like text. I know how that works. Excel doesn't care. 16 digit card numbers get their last digit turned into a zero, changed into scientific notation, stupid stuff that I did not tell Excel to do. I need to do things like Find/Remove spaces from cells in files downloaded from our currently imperfect web-system. The system sends me files with 16 digit numbers, cells formatted as text, but due to bugs there are spaces at the end. I do Find/Remove all spaces and all my card numbers are transformed into scientific notation and the last digit turned into a 0. THEY ARE TEXT, they are formatted as text, I yelled into the screen that they are text, why does Excel refuse to acknowledge that they are text? (I would rather find a way to stop Excel's action than find a way to tell our programmers to put an apostrophe in every cell) How do I make it so that Excel just STOPS doing anything that I didn't tell it to do? Or at least stop it from doing anything to numbers it doesn't like. Maybe I can write a macro for whenever it discovers "Uhoh I should change that number to something different!" I'll make it format that cell to text a thousand times instead. Give me an error when I try calculating with a number larger than 15 digits, make my computer explode violently, that's fine. Just stop changing the numbers. Is it possible? I have many thousands of numbers that need changing in many different scenarios. I just want to stop it from trying to help. I can't understand why that would be difficult. I have 2007, but answers for other versions would be great as well. Thank you!

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  • Classic ASP - Email form with attached file - please help

    - by apg1985
    Hi Guys, Ive got abit of a problem ive got an email web form that send the input to an email address but what I now need is a file input field were the user can also send an image as an attachment. So contact name, logo (attachment). Ive been told in order to send the attachment it needs to be saved in a folder on my hosting before it can be sent. Ive spoken to the hosting company and they dont have anything in place to make this easier such as aspupload. In the form name="contactname" and name="logo" I have a folder in the root directory called logos (this asp page also exists in the root directory) Man I hope someone can help me spent along time looking for answers Dim contactname, logo contactname = request.form("contactname") If request("contactname") <> "" THEN Set myMail=CreateObject("CDO.Message") myMail.Subject="Form" myMail.From="web@email" myMail.To="web@email" myMail.HTMLBody = "" & contactname & "" myMail.Configuration.Fields.Item("http://schemas.microsoft.com/cdo/configuration/sendusing") = 2 myMail.Configuration.Fields.Item("http://schemas.microsoft.com/cdo/configuration/smtpserver") = "relay.host" myMail.Configuration.Fields.Item("http://schemas.microsoft.com/cdo/configuration/smtpserverport") = 25 myMail.Configuration.Fields.Update myMail.Send set myMail=nothing

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  • Is there a way to make changes to toggles in my .emacs file apply without re-starting Emacs?

    - by Vivi
    I want to be able to make the changes to my .emacs file without having to reload Emacs. I found three questions which sort of answer what I am asking (you can find them here, here and here), but the problem is that the change I have just made is to a toggle, and as the comments to two of the answers (a1, a2) to those questions explain, the solutions given there (such as M-x reload-file or M-x eval-buffer) don't apply to toggles. I imagine there is a way of toggling the variable again with a command, but if there is a way to reload the whole .emacs and have the all the toggles re-evaluated without having to specify them, I would prefer. In any case, I would also appreciate if someone told me how to toggle the value of a variable so that if I just changed one toggle I can do it with a command rather than re-start Emacs just for that (I am new to Emacs). I don't know how useful this information is, but the change I applied was the following (which I got from this answer to another question): (setq skeleton-pair t) (setq skeleton-pair-on-word t) (global-set-key (kbd "[") 'skeleton-pair-insert-maybe) (global-set-key (kbd "(") 'skeleton-pair-insert-maybe) (global-set-key (kbd "{") 'skeleton-pair-insert-maybe) (global-set-key (kbd "<") 'skeleton-pair-insert-maybe) Edit: I included the above in .emacs and reloaded Emacs, so that the changes took effect. Then I commented all of it out and tried M-x load-file. This doesn't work. The suggestion below (C-x C-e by PP works if I am using it to evaluate the toggle first time, but not when I want to undo it). I would like something that would evaluate the commenting out, if such thing exists... Thanks :)

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  • Automatic .NET code, nhibernate session, and LINQ datacontext clean-up?

    - by AverageJoe719
    Hi all, in my goal to adopt better coding practices I have a few questions in general about automatic handling of code. I have heard different answers both from online and talking with other developers/programmers at my work. I am not sure if I should have split them into 3 questions, but they all seem sort of related: 1) How does .NET handle instances of classes and other code things that take up memory? I recently found out about using the factory pattern for certain things like service classes so that they are only instantiated once in the entire application, but then I was told that '.NET handles a lot of that stuff automatically when mentioning it.' 2) How does Nhibernate's session handle automatic clean-up of un-used things? I've seen some say that it is great at handling things automatically and you should just use a session factory and that's it, no need to close it. But I have also read and seem many examples where people close the hibernate session. 3) How does LINQ's datacontext handle this? Most of the time I never .disposed my datacontext's and the app didn't see to take a performance hit (though I am not running anything super intensively), but it seems like most people recommend disposing of your datacontext after you are done with it. However, I have seen many many code examples where the dispose method is never called. Also in general I found it kind of annoying that you couldn't access even one-deep child related objects after disposing of the datacontext unless you explicity also grabbed them in the query. Thanks all. I am loving this site so far, I kind of get lost and spend hours just reading things on here. =)

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  • Why is creating a ring buffer shared by different processes so hard (in C++), what I am doing wrong?

    - by recipriversexclusion
    I am being especially dense about this but it seems I'm missing an important, basic point or something, since what I want to do should be common: I need to create a fixed-size ring buffer object from a manager process (Process M). This object has write() and read() methods to write/read from the buffer. The read/write methods will be called by independent processes (Process R and W) I have implemented the buffer, SharedBuffer<T&>, it allocates buffer slots in SHM using boost::interprocess and works perfectly within a single process. I have read the answers to this question and that one on SO, as well as asked my own, but I'm still in the dark about how to have different processes access methods from a common object. The Boost doc has an example of creating a vector in SHM, which is very similar to what I want, but I want to instantiate my own class. My current options are: Use placement new, as suggested by Charles B. to my question; however, he cautions that it's not a good idea to put non-POD objects in SHM. But my class needs the read/write methods, how can I handle those? Add an allocator to my class definition, e.g. have SharedBuffer<T&, Alloc> and proceed similarly to the vector example given in boost. This sounds really complicated. Change SharedBuffer to a POD class, i.e. get rid of all the methods. But then how to synchronize reading and writing between processes? What am I missing? Fixed-length ring buffers are very common, so either this problem has a solution or else I'm doing something wrong.

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  • Checking inherited attributes in an 'ancestry' based SQL table

    - by Brendon Muir
    I'm using the ancestry gem to help organise my app's tree structure in the database. It basically writes a childs ancestor information to a special column called 'ancestry'. The ancestry column for a particular child might look like '1/34/87' where the parent of this child is 87, and then 87's parent is 34 and 34's is 1. It seems possible that we could select rows from this table each with a subquery that checks all the ancestors to see if a certain attribute it set. E.g. in my app you can hide an item and its children just by setting the parent element's visibility column to 0. I want to be able to find all the items where none of their ancestors are hidden. I tried converting the slashes to comma's with the REPLACE command but IN required a set of comma separated integers rather than one string with comma separated string numbers. It's funny, because I can do this query in two steps, e.g. retrieve the row, then take its ancestry column, split out the id's and make another query that checks that the id is IN that set of id's and that visibility isn't ever 0 and whala! But joining these into one query seems to be quite a task. Much searching has shown a few answers but none really do what I want. SELECT * FROM t1 WHERE id = 99; 99's ancestry column reads '1/34/87' SELECT * FROM t1 WHERE visibility = 0 AND id IN (1,34,87); kind of backwards, but if this returns no rows then the item is visible. Has anyone come across this before and come up with a solution. I don't really want to go the stored procedure route. It's for a rails app.

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  • How to get smartcard reader name in Windows 7 using C# or C/C++?

    - by AndrejaKo
    Hi! I'm trying to make a C# program which will use a C .dll (unfortunately, the .dll doesn't have good documentation) to access a smart card. One of the functions of the .dll uses name of the reader as argument. My problem is that I don't know how to get the name. After looking for answers I found something similar to what I need in an example here: http://msdn.microsoft.com/en-us/library/aa379803%28VS.85%29.aspx I'm looking for a way to get szReader value as described in the aforementioned example using C#. Can anyone help me or at least point me in the right direction? EDIT: Looks like nobody knows the answer so I'll expand the question: How do I get smartcard reader name using C/C++ and Windows API? I've read through MSDN site for smartcard API, but I couldn't find the function which will list readers. My idea is now to make a C/C++ .dll which will get in-between the smartcard .dll and C# program. It will produce list of readers, let user chose one and call the smartcard .dll using chosen name as argument.

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  • How do I add and remove an event listener using a function with parameters?

    - by Bungle
    Sorry if this is a common question, but I couldn't find any answers that seemed pertinent through searching. If I attach an event listener like this: window.addEventListener('scroll', function() { check_pos(box); }, false); it doesn't seem to work to try to remove it later, like this: window.removeEventListener('scroll', function() { check_pos(box); }, false); I assume this is because the addEventListener and removeEventListener methods want a reference to the same function, while I've provided them with anonymous functions, which, while identical in code, are not literally the same. How can I change my code to get the call to removeEventListener to work? The "box" argument refers to the name of an <iframe> that I'm tracking on the screen; that is, I want to be able to subscribe to the scroll event once for each <iframe> that I have (the quantity varies), and once the check_pos() function measures a certain position, it will call another function and also remove the event listener to free up system resources. My hunch is that the solution will involve a closure and/or naming the anonymous function, but I'm not sure exactly what that looks like, and would appreciate a concrete example. Hope that makes sense. Thanks for any help!

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  • MYSQL not running on Ubuntu OS - Error 2002.

    - by mgj
    Hi, I am a novice to mysql DB. I am trying to run the MYSQL Server on Ubuntu 10.04. Through Synaptic Package Manager I am have installed the mysql version: mysql-client-5.1 I wonder that how was the database password set for the mysql-client software that I installed through the above way.It would be nice if you could enlighten me on this. When I tried running this database, I encountered the error given below: mohnish@mohnish-laptop:/var/lib$ mysql ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) mohnish@mohnish-laptop:/var/lib$ I referred to a similar question posted by another user. I didn't find a solution through the proposed answers. For instance when I tried the solutions posted for the similar question I got the following: mohnish@mohnish-laptop:/var/lib$ service start mysqld start: unrecognized service mohnish@mohnish-laptop:/var/lib$ ps -u mysql ERROR: User name does not exist. ********* simple selection ********* ********* selection by list ********* -A all processes -C by command name -N negate selection -G by real group ID (supports names) -a all w/ tty except session leaders -U by real user ID (supports names) -d all except session leaders -g by session OR by effective group name -e all processes -p by process ID T all processes on this terminal -s processes in the sessions given a all w/ tty, including other users -t by tty g OBSOLETE -- DO NOT USE -u by effective user ID (supports names) r only running processes U processes for specified users x processes w/o controlling ttys t by tty *********** output format ********** *********** long options *********** -o,o user-defined -f full --Group --User --pid --cols --ppid -j,j job control s signal --group --user --sid --rows --info -O,O preloaded -o v virtual memory --cumulative --format --deselect -l,l long u user-oriented --sort --tty --forest --version -F extra full X registers --heading --no-heading --context ********* misc options ********* -V,V show version L list format codes f ASCII art forest -m,m,-L,-T,H threads S children in sum -y change -l format -M,Z security data c true command name -c scheduling class -w,w wide output n numeric WCHAN,UID -H process hierarchy mohnish@mohnish-laptop:/var/lib$ which mysql /usr/bin/mysql mohnish@mohnish-laptop:/var/lib$ mysql ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) I even tried referring to http://forums.mysql.com/read.php?11,27769,84713#msg-84713 but couldn't find anything useful. Please let me know how I could tackle this error. Thank you very much..

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  • Does git clone work through NTLM proxies?

    - by AndreaG
    I've tried both using export http_proxy=http://[username]:[pwd]@[proxy] and git config --global http.proxy http://[username]:[pwd]@[proxy]. I couldn't make it work. It looks like git uses Basic authentication: Initialized empty Git repository in /home/.../.git/ * Couldn't find host github.com in the .netrc file, using defaults * About to connect() to github.com port 8080 (#0) * Trying 10.... * Connected to github.com (10....) port 8080 (#0) * Proxy auth using Basic with user '...' > GET http://github.com/sunlightlabs/fiftystates.git/info/refs HTTP/1.1 Proxy-Authorization: Basic MD... User-Agent: git/1.6.1.2 Host: github.com Pragma: no-cache Accept: */* Proxy-Connection: Keep-Alive < HTTP/1.1 407 Proxy Authentication Required ( The ISA Server requires authorization to fulfill the request. Access to t he Web Proxy filter is denied. ) < Via: 1.1 ... < Proxy-Authenticate: Negotiate < Proxy-Authenticate: Kerberos < Proxy-Authenticate: NTLM < Connection: Keep-Alive < Proxy-Connection: Keep-Alive < Pragma: no-cache < Cache-Control: no-cache < Content-Type: text/html < Content-Length: 4118 * The requested URL returned error: 407 * Closing connection #0 fatal: http://github.com/sunlightlabs/fiftystates.git/info/refs download error - The requested URL returned error: 407 Google search returned mixed and probably not updated results. Somewhere it says that curl is (was?) used under the hood, but its options are (were?) hardwired into code. For example, curl --proxy-ntlm --proxy ...:8080 google.com works, and I'd like to use the same option with git. I need some more definite answers here: has anybody succeed using git through Windows proxies? Which version? Thanks.

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  • Javascript Object.Watch for all browsers?

    - by SeanW
    Hey all, I was looking for an easy way to monitor an object or variable for changes, and I found Object.Watch that's supported in Mozilla browsers, but not IE. So I started searching around to see if anyone had written some sort of equivalent. About the only thing I've found has been a jQuery plugin (http://plugins.jquery.com/files/jquery-watch.js.txt), but I'm not sure if that's the best way to go. I certainly use jQuery in most of my projects, so I'm not worried about the jQuery aspect... Anyway, the question: can someone show me a working example of that jQuery plugin? I'm having problems making it work... Or, does anyone know of any better alternatives that would work cross browser? Thanks! Update after answers: Thanks everyone for the responses! I tried out the code posted here: http://webreflection.blogspot.com/2009/01/internet-explorer-object-watch.html But I couldn't seem to make it work with IE. The code below works fine in FireFox, but does nothing in IE. In Firefox, each time watcher.status is changed, the document.write in watcher.watch is called and you can see the output on the page. In IE, that doesn't happen, but I can see that watcher.status is updating the value, because the last document.write shows the correct value (in both IE and FF). But, if the callback function isn't called, then that's kind of pointless... :) Am I missing something? var options = {'status': 'no status'}, watcher = createWatcher(options); watcher.watch("status", function(prop, oldValue, newValue) { document.write("old: " + oldValue + ", new: " + newValue + "<br>"); return newValue; }); watcher.status = 'asdf'; watcher.status = '1234'; document.write(watcher.status + "<br>");

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  • Help with possible Haskell type inference quiz questions

    - by Linda Cohen
    foldr:: (a -> b -> b) -> b -> [a] -> b map :: (a -> b) -> [a] -> [b] mys :: a -> a (.) :: (a -> b) -> (c -> a) -> c -> b what is inferred type of: a.map mys :: b.mys map :: c.foldr map :: d.foldr map.mys :: I've tried to create mys myself using mys n = n + 2 but the type of that is mys :: Num a => a -> a What's the difference between Num a = a - a and just a - a? Or what does 'Num a =' mean? Is it that mys would only take Num type? So anyways, a) I got [a] - [a] I think because it would just take a list and return it +2'd according to my definition of mys b) (a - b) - [a] - [b] I think because map still needs take both arguments like (*3) and a list then returns [a] which goes to mys and returns [b] c) I'm not sure how to do this 1. d) I'm not sure how to do this 1 either but map.mys means do mys first then map right? Are my answers and thoughts correct? If not, why not? THANKS!

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  • Cassandra hot keyspace structure change

    - by Pierre
    Hello. I'm currently running a 12-node Cassandra cluster storing 4TB of data, with a replication factor set to 3. For the needs of an application update, we need to change the configuration of our keyspace, and we'd like to avoid any downtime if possible. I read on a mailing list that the best way to do it is to: Kill cassandra process on one server of the cluster Start it again, wait for the commit log to be written on the disk, and kill it again Make the modifications in the storage.xml file Rename or delete the files in the data directories according to the changes we made Start cassandra Goto 1 with next server on the list My questions would be: Did I understand the process well? Is there any risk of data corruption? During the process, there will be servers with different versions of the storage.xml file in the same cluser, same keyspace. Is it a problem? Same question as above if we not only add, rename and remove ColumnFamilies, but if we change the CompareWith parameter / transform an existing column family into a super one. Or do we need to change the name? Thank you for your answers. It's the first time I'll do this, and I'm a little bit scared.

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  • Removing elements using XSLT 1.0

    - by pmdarrow
    I'm attempting to remove Component elements from the XML below that have File children with the extension "config." I've managed to do this part, but I also need to remove the matching ComponentRef elements that have the same IDs as these Components. <Fragment> <DirectoryRef Id="MyWebsite"> <Component Id="Comp1"> <File Source="Web.config" /> </Component> <Component Id="Comp2"> <File Source="Default.aspx" /> </Component> </DirectoryRef> </Fragment> <Fragment> <ComponentGroup Id="MyWebsite"> <ComponentRef Id="Comp1" /> <ComponentRef Id="Comp2" /> </ComponentGroup> </Fragment> Based on other SO answers, I've come up with the following XSLT to remove these Component elements: <?xml version="1.0" encoding="utf-8"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:output method="xml" indent="yes" /> <xsl:template match="Component[File[substring(@Source, string-length(@Source)- string-length('config') + 1) = 'config']]" /> <xsl:template match="@*|node()"> <xsl:copy> <xsl:apply-templates select="@*|node()"/> </xsl:copy> </xsl:template> </xsl:stylesheet> Unfortunately, this doesn't remove the matching ComponentRef elements. The XSLT will remove the component with the Id "Comp1" but not the ComponentRef with Id "Comp1". How do I achieve this using XSLT 1.0?

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  • How would you go about parsing markdown?

    - by John Leidegren
    You can find the syntax here. The thing is, the source that follows with the download is written in perl. Which I have no intentions of honoring. It is riddled with regex and it relies on MD5 hashes to escape certain characters. Something is just wrong about that! I'm about to hard code a parser for markdown and I'm wonder if someone had some experience with this? Edit: If you don't have anything meaningful to say about the actual parsing of markdown, spare me the time. (This might sound harsh, but yes, I'm looking for insight, not a solution i.e. third-party library). To help a bit with the answers, regex are meant to identify patterns! NOT to parse an entire grammar. That people consider doing so is foobar. If you think about markdown, it's fundamentally based around the concept of paragraphs. As such, a reasonable approach might be to split the input into paragraphs. There are many kinds of paragraphs e.g. heading, text, list, blockquote, code. The challenge is thus to identify these paragraphs and in what context they occur. I'll be back with a solution, once I find it's worthy to be shared.

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  • Javascript: "Dangling" Reference to DOM element?

    - by Channel72
    It seems that in Javascript, if you have a reference to some DOM element, and then modify the DOM by adding additional elements to document.body, your DOM reference becomes invalidated. Consider the following code: <html> <head> <script type = "text/javascript"> function work() { var foo = document.getElementById("foo"); alert(foo == document.getElementById("foo")); document.body.innerHTML += "<div>blah blah</div>"; alert(foo == document.getElementById("foo")); } </script> </head> <body> <div id = "foo" onclick='work()'>Foo</div> </body> </html> When you click on the DIV, this alerts "true", and then "false." So in other words, after modifying document.body, the reference to the DIV element is no longer valid. This behavior is the same on Firefox and MSIE. Some questions: Why does this occur? Is this behavior specified by the ECMAScript standard, or is this a browser-specific issue? Note: there's another question posted on stackoverflow that seems to be referring to the same issue, but neither the question nor the answers are very clear.

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  • Creating a smart text generator

    - by royrules22
    I'm doing this for fun (or as 4chan says "for teh lolz") and if I learn something on the way all the better. I took an AI course almost 2 years ago now and I really enjoyed it but I managed to forget everything so this is a way to refresh that. Anyway I want to be able to generate text given a set of inputs. Basically this will read forum inputs (or maybe Twitter tweets) and then generate a comment based on the learning. Now the simplest way would be to use a Markov Chain Text Generator but I want something a little bit more complex than that as the MKC basically only learns by word order (which word is more likely to appear after word x given the input text). I'm trying to see if there's something I can do to make it a little bit more smarter. For example I want it to do something like this: Learn from a large selection of posts in a message board but don't weight it too much For each post: Learn from the other comments in that post and weigh these inputs higher Generate comment and post See what other users' reaction to your post was. If good weigh it positively so you make more posts that are similar to the one made, and vice versa if negative. It's the weighing and learning from mistakes part that I'm not sure how to implement. I thought about Artificial Neural Networks (mainly because I remember enjoying that chapter) but as far as I can tell that's mainly used to classify things (i.e. given a finite set of choices [x1...xn] which x is this given input) not really generate anything. I'm not even sure if this is possible or if it is what should I go about learning/figuring out. What algorithm is best suited for this? To those worried that I will use this as a bot to spam or provide bad answers to SO, I promise that I will not use this to provide (bad) advice or to spam for profit. I definitely will not post it's nonsensical thoughts on SO. I plan to use it for my own amusement. Thanks!

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  • Use AJAX to reload captcha

    - by arik-so
    Hello! This question may have been asked already - but unfortunately, I could not find any satisfactory answers. I will just ask it for my concrete case and ask the admins not to delete the question for at least a few days so I can try it out... I have a page. It uses a captcha. Like so: <?php session_start(); // the captcha saves the md5 into the session ?> <img src="captcha.php" onclick="this.src = this.src" /> That was my first code. It did not work, because the browser condsidered it useless to reload an image if the source is the same. My current solution is to pass a get parameter: onclick="this.src = 'captcha.php?randomNumber='+ranNum" The JavaScript variable var ranNum is generated randomly every time the onclick event fires. It works fine, still, I don't like the possibility, if the - though improbable - case of two numbers being the same twice in a row. Although the random number varies between -50,000 and 50,000 - I still do not like it. And I don't think the method is right. I would like to know the 'righter' method, by means of AJAX. I know it's possible. I hope you know how it's possible ^^ In that case, please show me. Thanks in advance! By the way - if I spell cap(t)cha differently, never mind, the reference to the PHP file is right in my code: I use randomImage.php

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