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  • Retain cycle on `self` with blocks

    - by Jonathan Sterling
    I'm afraid this question is pretty basic, but I think it's relevant to a lot of Objective-C programmers who are getting into blocks. What I've heard is that since blocks capture local variables referenced within them as const copies, using self within a block can result in a retain cycle, should that block be copied. So, we are supposed to use __block to force the block to deal directly with self instead of having it copied. __block typeof(self) bself = self; [someObject messageWithBlock:^{ [bself doSomething]; }]; instead of just [someObject messageWithBlock:^{ [self doSomething]; }]; What I'd like to know is the following: if this is true, is there a way that I can avoid the ugliness (aside from using GC)?

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  • What to keep in mind when creating your own custom web services API?

    - by John Conde
    I have created a website which allows users to sign up for, and use, an online service. To help promote the website we will be have resellers who will be offering their own branded services through us. The initial plan is to allow resellers to place registration, login, and lost password forms on their own website and use an API created by us to handle these requests. I have begun outlining how I expect the API to work (and starting documenting it as well) and I want to make sure I get it right, or as close to right, as I can from the beginning as I know once you have declared a public API you want to avoid changing that API at all costs. So far I have decided: To have the user pass their account credentials with each request To require SSL for all requests What else should I be keeping in mind?

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  • 2 way communication over http between a .Net service and Windows Forms Client

    - by user1802969
    I am looking to accomplish 2 way communication over http between a .Net service (WCF SOAP or REST, both options are open) hosted on IIS 7 and Windows Forms Client running on Windows 7. WebSockets are not supported with IIS 7 and all other Comet techniques allow only the web server to push data to client and not the other way around. The client will be very chatty, and there are thousands of clients, so I want to avoid creating a new HTTP request for each message to the server, though that is the last option. Is there any way to do this ?

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  • Is there such a thing as a converter from php to html?

    - by 0plus1
    Don't think that I'm mad, I understand how php works! That being said. I develop personal website and I usually take advantage of php to avoid repetion during the development phase nothing truly dynamic, only includes for the menus, a couple of foreach and the likes. When the development phase ends I need to give the website in html files to the client. Is there a tool (crawler?) that can do this for me instead of visiting each page and saving the interpreted html?

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  • cd Terminal at a given directory after running a Python script?

    - by Dave Everitt
    I'm working on a simple Python script that can use subprocess and/or os to execute some commands, which is working fine. However, when the script exits I'd like to cd the actual Terminal (in this case OS X) so on exit, the new files are ready to use in the directory where the have been created. All the following (subprocess.Popen, os.system, os.chdir) can do what I want from within the script (i.e. they execute stuff in the target directory) but on exit leave the Terminal at the script's own directory, not the target directory. I'd like to avoid writing a shell script to temporary file just to achieve this, if this is at all possible anyway?

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  • How to use Map element as text of a JComboBox

    - by llm
    I am populating a JComboBox (using addItem()) with all the elements of a collection. Each element in the collection is a HashMap (so its a ComboBox of Hashmaps..). My question is - Given that I need each item to be a HashMap how do I set the text to apear in the combobox on the GUI? It needs to be the value of a certain key in the map. Normally if I am populating a combobox with my own type, I would just overide the toString() method...but I am not sure how to acheive this since I am using a Java HashMap. Any ideas (if possible, without implementing my own HashMap)? Update: It seems like there isn't anyway to avoid having the object int the JComboBox overide toString() if I want custom functionality..I wish there was a way to (1) specify the objects to be loaded into the JComboBox and (2) specify how these objects are to appear in the GUI.

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  • Scoping in embedded groovy scripts

    - by Aaron Digulla
    In my app, I use Groovy as a scripting language. To make things easier for my customers, I have a global scope where I define helper classes and constants. Currently, I need to run the script (which builds the global scope) every time a user script is executed: context = setupGroovy(); runScript( context, "global.groovy" ); // Can I avoid doing this step every time? runScript( context, "user.groovy" ); Is there a way to setup this global scope once and just tell the embedded script interpreter: "Look here if you can't find a variable"? That way, I could run the global script once. Note: Security is not an issue here but if you know a way to make sure the user can't modify the global scope, that's an additional plus.

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  • List of divisors of an integer n (Haskell)

    - by Code-Guru
    I currently have the following function to get the divisors of an integer: -- All divisors of a number divisors :: Integer -> [Integer] divisors 1 = [1] divisors n = firstHalf ++ secondHalf where firstHalf = filter (divides n) (candidates n) secondHalf = filter (\d -> n `div` d /= d) (map (n `div`) (reverse firstHalf)) candidates n = takeWhile (\d -> d * d <= n) [1..n] I ended up adding the filter to secondHalf because a divisor was repeating when n is a square of a prime number. This seems like a very inefficient way to solve this problem. So I have two questions: How do I measure if this really is a bottle neck in my algorithm? And if it is, how do I go about finding a better way to avoid repetitions when n is a square of a prime?

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  • Python Library installation

    - by MacPython
    Hi everybody I have two questions regarding python libraries: I would like to know if there is something like a "super" python library which lets me install ALL or at least all scientific useful python libraries, which I can install once and then I have all I need. There is a number of annoying problems when installing different libraries (pythonpath, cant import because it is not installed BUT it is installed). Is there any good documentation about common installation errors and how to avoid them. If there is no total solution I would be interested in numpy, scipy, matplotlib, PIL Thanks a lot for the attention and help Best Z

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  • Writing to the middle of the file (without overwriting data)

    - by Andreas Bonini
    In windows is it possible through an API to write to the middle of a file without overwriting any data and without having to rewrite everything after that? If it's possible then I believe it will obviously fragment the file; how many times can I do it before it becomes a serious problem? If it's not possible what approach/workaround is usually taken? Re-writing everything after the insertion point becomes prohibitive really quickly with big (ie, gigabytes) files. Note: I can't avoid having to write to the middle. Think of the application as a text editor for huge files where the user types stuff and then saves. I also can't split the files in several smaller ones.

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  • How do I implement .net plugins without using AppDomains?

    - by Abtin Forouzandeh
    Problem statement: Implement a plug-in system that allows the associated assemblies to be overwritten (avoid file locking). In .Net, specific assemblies may not be unloaded, only entire AppDomains may be unloaded. I'm posting this because when I was trying to solve the problem, every solution made reference to using multiple AppDomains. Multiple AppDomains are very hard to implement correctly, even when architected at the start of a project. Also, AppDomains didn't work for me because I needed to transfer Type across domains as a setting for Speech Server worfklow's InvokeWorkflow activity. Unfortunately, sending a type across domains causes the assembly to be injected into the local AppDomain. Also, this is relevant to IIS. IIS has a Shadow Copy setting that allows an executing assembly to be overwritten while its loaded into memory. The problem is that (at least under XP, didnt test on production 2003 servers) when you programmatically load an assembly, the shadow copy doesnt work (because you are loading the DLL, not IIS).

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  • Creating a Java platform game as easily as possible

    - by directx
    I need to create a Java-based platformer game for a high school project (not computer science related), and I want to spend as little time on technical stuff as possible. I'm already experienced in Java, and I already have most of the gameplay, graphics, etc. All I need to do is code it. I've looked and I'm considering one of two options that do not involving coding a game from scratch: Copy an existing Java platformer (best option, but I can't find an open source Java platformer) Use a Java game engine to avoid coding from scratch. I've looked at JGame but I'm not sure if it's the best bet for a platformer.

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  • What do gurus say about Requirements Traceability Matrix?

    - by Jaywalker
    Our organization is at CMMI Level 2, and as part of the requirements of the level, we have to maintain an RTM which more or less contains the following entries for each requirement: Requirement Description Reference Section Functional Specification Document Reference Section Design Document Reference Section Test Cases Document Now, this might be an overkill for a small project. But more importantly, this could be a nightmare to maintain when the requirements/ features keep changing, and documents have to be constantly updated. What do the gurus say about this? Should one avoid such level of documentation or are there any tools to manage when a "change" out dates so many artifacts? And by using the term 'gurus', I am not talking of coding champs; rather people like Steve McConnel or others who have worked on commercial projects of medium to large scale. Quotes/ book references/ articles will suit me. EDIT: It's not just requirements that change. Design Document can change; well, even test cases may change.

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  • How do you resolve the common naming collision between type and object?

    - by Catskul
    Since the standard c# convention is to capitalize the first letter of public properties, the old c++ convention of initial capital for type names, and initial lowercase for non-type names does not prevent the classic name collision where the most obvious object name matches the type name: class FooManager { public BarManager BarManager { get; set; } // Feels very wrong. // Recommended naming convention? public int DoIt() { // 1st and 2nd Bar Manager are different symbols return BarManager.Blarb + BarManager.StaticBlarb; } } class BarManager { public int Blarb { get; set; } public static int StaticBlarb { get; set; } } It seems to compile, but feels so wrong. Is there a recommend naming convention to avoid this?

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  • How to prevent UI from freezing during lengthy process?

    - by OverTheRainbow
    Hello, I need to write a VB.Net 2008 applet to go through all the fixed-drives looking for some files. If I put the code in ButtonClick(), the UI freezes until the code is done: Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click 'TODO Find way to avoid freezing UI while scanning fixed drives Dim drive As DriveInfo Dim filelist As Collections.ObjectModel.ReadOnlyCollection(Of String) Dim filepath As String For Each drive In DriveInfo.GetDrives() If drive.DriveType = DriveType.Fixed Then filelist = My.Computer.FileSystem.GetFiles(drive.ToString, FileIO.SearchOption.SearchAllSubDirectories, "MyFiles.*") For Each filepath In filelist 'Do stuff Next filepath End If Next drive End Sub Google returned information on a BackGroundWorker control: Is this the right/way to solve this issue? If not, what solution would you recommend, possibly with a really simple example? FWIW, I read that Application.DoEvents() is a left-over from VBClassic and should be avoided. Thank you.

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  • Is it possible to dynamically set a static string during *class* Initialisation?

    - by LonnieBest
    I'm trying to dynamically create a connection string during compile time: public static string ConnectionString { get { string connectionString = @"Data Source=" + myLibrary.common.GetExeDir() + @"\Database\db.sdf;"; return connectionString; } } I keep running into type initialisation errors. I was trying to avoid having to set the connection string for all applications that user my code library. The location of the database is different for each project that uses the library. I have code that can determine the correction string, but was wanting run it during compile time. Is this even possible?

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  • Planning a competition

    - by Jérôme
    I need to produce the schedule of a sport-event. There are 30 teams. Each team has to play 8 matches. This means that it is not possible for each team to compete again all other teams, but I need to avoid that two team compete more than once against each other. My idea was to generate all possible matches (for 30 teams: (30*29)/2 = 435 matches) and select from this list 120 matches (8 match for each team: 8 * 30 / 2 = 120 matches). This is where I'm having a hard time: how can I select these 120 matches? I tried some simple solutions (take first match of the list, then the last, and so on) but they don't seem to work with 30 teams. I also tried to generate all possible match combination and find which one is working but with 30 team, this is too much calculation time. Is there an existing algorithm that I could implement?

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  • How to sanely read and dump structs to disk when some fields are pointers?

    - by bp
    Hello, I'm writing a FUSE plugin in C. I'm keeping track of data structures in the filesystem through structs like: typedef struct { block_number_t inode; filename_t filename; //char[SOME_SIZE] some_other_field_t other_field; } fs_directory_table_item_t; Obviously, I have to read (write) these structs from (to) disk at some point. I could treat the struct as a sequence of bytes and do something like this: read(disk_fd, directory_table_item, sizeof(fs_directory_table_item_t)); ...except that cannot possibly work as filename is actually a pointer to the char array. I'd really like to avoid having to write code like: read(disk_df, *directory_table_item.inode, sizeof(block_number_t)); read(disk_df, directory_table_item.filename, sizeof(filename_t)); read(disk_df, *directory_table_item.other_field, sizeof(some_other_field_t)); ...for each struct in the code, because I'd have to replicate code and changes in no less than three different places (definition, reading, writing). Any DRYer but still maintainable ideas?

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  • Heavy use of templates for mobile platforms

    - by Chris P. Bacon
    I've been flicking through the book Modern C++ Design by Andrei Alexandrescu and it seems interesting stuff. However it makes very extensive use of templates and I would like to find out if this should be avoided if using C++ for mobile platform development (Brew MP, WebOS, iOS etc.) due to size considerations. In Symbian OS C++ the standard use of templates is discouraged, the Symbian OS itself uses them but using an idiom known as thin templates where the underlying implementation is done in a C style using void* pointers with a thin template layered on top of this to achieve type safety. The reason they use this idiom as opposed to regular use of templates is specifically to avoid code bloating. So what are opinions (or facts) on the use of templates when developing applications for mobile platforms.

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  • Does it make a difference in performance if I use self.fooBar instead of fooBar?

    - by mystify
    Note: I know exactly what a property is. This question is about performance. Using self.fooBar for READ access seems a waste of time for me. Unnecessary Objective-C messaging is going on. The getters typically simply pass along the ivar, so as long as it's pretty sure there will be no reasonable getter method written, I think it's perfectly fine to bypass this heavy guy. Objective-C messaging is about 20 times slower than direct calls. So if there is some high-performance-high-frequency code with hundreds of properties in use, maybe it does help a lot to avoid unnessessary objective-c messaging? Or am I wasting my time thinking about this?

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  • AS3: creating a class with multiple and optional parameters?

    - by redconservatory
    I'm creating a slideshow where each slide can have: - a video or a still - 1 audio track or many (up to 3) - 1 button or many (up to 3) I was thinking that each slide can be it's own object, and then I would pass the video, audio, buttons, etc., into it as parameters: package { import flash.media.Video; public class Section { public function Section (video:Video, still:myPhotoClass, audiotrack:Sound, button:myButtonClass) { // can have video OR a still // can have 1 audio track or several // can have 1 button or more } } I'm not sure how to go about approaching this since there can be multiples of certain items (audio, buttons) and also two items are sort-of-optional in the sense that there can be ONE or the OTHER (video/still). For example, is this something that I should just avoid passing as parameters altogether, using a different approach (getters/setters, maybe)?

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  • ASP.NET single quotes are converted to &#39;

    - by Monty
    Note: Most probably this will be a double question, but since I haven't found a clear answer, I'm asking it anyway. In ASP.NET I'd like to add some JavaScript to the onclick event of a CheckBox. I've simplified the case to this: <asp:CheckBox ID="TestCheckBox" runat="server" onclick="alert('test');" Text="Test" /> The resulting HTML is as follows: <input id="MainContainer_TestCheckBox" type="checkbox" name="ctl00$MainContainer$TestCheckBox" onclick="alert(&#39;test&#39;);" /><label for="MainContainer_TestCheckBox">Test</label> What particularly bothers me is that a single quote 'automatically' gets converted into '&#39;'. If I omit the onclick in the markup and assign it in Page_Load, the exact same results show in the HTML. protected void Page_Load(object sender, EventArgs e) { this.TestCheckBox.Attributes["onclick"] = "alert('test');"; } Anyone got a clue about what's happening? Or how to fix/ avoid it?

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  • Import module stored in a cStringIO data structure vs. physical disk file

    - by Malcolm
    Is there a way to import a Python module stored in a cStringIO data structure vs. physical disk file? It looks like "imp.load_compiled(name, pathname[, file])" is what I need, but the description of this method (and similar methods) has the following disclaimer: Quote: "The file argument is the byte-compiled code file, open for reading in binary mode, from the beginning. It must currently be a real file object, not a user-defined class emulating a file." [1] I tried using a cStringIO object vs. a real file object, but the help documentation is correct - only a real file object can be used. Any ideas on why these modules would impose such a restriction or is this just an historical artifact? Are there any techniques I can use to avoid this physical file requirement? Thanks, Malcolm [1] http://docs.python.org/library/imp.html#imp.load_module

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  • Python IDLE freezes

    - by ooboo
    This is absolutely frustrating, but I am not sure if the following is an issue only on my machine or with IDLE in general. When attempting to print a long list in the shell, and that could happen by accident while debugging, the program crushes and you have to restart it manually. Even worse, if you have a few editor windows open, it always spawns a few sub-processes, and each of these has to be manually shut down from the task manager. Is there any way to avoid that? I am using Python 3, by the way.

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  • Html encoding in MVC input

    - by fearofawhackplanet
    I'm working through NerdDinner and I'm a bit confused about the following section... First they've added a form for creating a new dinner, with a bunch of textboxes delcared like: <%= Html.TextArea("Description") %> They then show two ways of binding form input to the model: [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create() { Dinner dinner = new Dinner(); UpdateModel(dinner); ... } or: [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create(Dinner dinner) { ... } Ok, great, that all looks really easy so far. Then a bit later on they say: It is important to always be paranoid about security when accepting any user input, and this is also true when binding objects to form input. You should be careful to always HTML encode any user-entered values to avoid HTML and JavaScript injection attacks Huh? MVC is managing the data binding for us. Where/how are you supposed to do the HTML encoding?

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