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  • Algorithm to produce Cartesian product of arrays in depth-first order

    - by Yuri Gadow
    I'm looking for an example of how, in Ruby, a C like language, or pseudo code, to create the Cartesian product of a variable number of arrays of integers, each of differing length, and step through the results in a particular order: So given, [1,2,3],[1,2,3],[1,2,3]: [1, 1, 1] [2, 1, 1] [1, 2, 1] [1, 1, 2] [2, 2, 1] [1, 2, 2] [2, 1, 2] [2, 2, 2] [3, 1, 1] [1, 3, 1] etc. Instead of the typical result I've seen (including the example I give below): [1, 1, 1] [2, 1, 1] [3, 1, 1] [1, 2, 1] [2, 2, 1] [3, 2, 1] [1, 3, 1] [2, 3, 1] etc. The problem with this example is that the third position isn't explored at all until all combinations of of the first two are tried. In the code that uses this, that means even though the right answer is generally (the much larger equivalent of) 1,1,2 it will examine a few million possibilities instead of just a few thousand before finding it. I'm dealing with result sets of one million to hundreds of millions, so generating them and then sorting isn't doable here and would defeat the reason for ordering them in the first example, which is to find the correct answer sooner and so break out of the cartesian product generation earlier. Just in case it helps clarify any of the above, here's how I do this now (this has correct results and right performance, but not the order I want, i.e., it creates results as in the second listing above): def cartesian(a_of_a) a_of_a_len = a_of_a.size result = Array.new(a_of_a_len) j, k, a2, a2_len = nil, nil, nil, nil i = 0 while 1 do j, k = i, 0 while k < a_of_a_len a2 = a_of_a[k] a2_len = a2.size result[k] = a2[j % a2_len] j /= a2_len k += 1 end return if j > 0 yield result i += 1 end end UPDATE: I didn't make it very clear that I'm after a solution where all the combinations of 1,2 are examined before 3 is added in, then all 3 and 1, then all 3, 2 and 1, then all 3,2. In other words, explore all earlier combinations "horizontally" before "vertically." The precise order in which those possibilities are explored, i.e., 1,1,2 or 2,1,1, doesn't matter, just that all 2 and 1 are explored before mixing in 3 and so on.

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  • How to load JPG file into NSBitmapImageRep?

    - by Adam
    Objective-C / Cocoa: I need to load the image from a JPG file into a two dimensional array so that I can access each pixel. I am trying (unsuccessfully) to load the image into a NSBitmapImageRep. I have tried several variations on the following two lines of code: NSString *filePath = [NSString stringWithFormat: @"%@%@",@"/Users/adam/Documents/phoneimages/", [outLabel stringValue]]; //this coming from a window control NSImageRep *controlBitmap = [[NSImageRep alloc] imageRepWithContentsOfFile:filePath]; With the code shown, I get a runtime error: -[NSImageRep imageRepWithContentsOfFile:]: unrecognized selector sent to instance 0x100147070. I have tried replacing the second line of code with: NSImage *controlImage = [[NSImage alloc] initWithContentsOfFile:filePath]; NSBitmapImageRep *controlBitmap = [[NSBitmapImageRep alloc] initWithData:controlImage]; But this yields a compiler error 'incompatible type' saying that initWithData wants a NSData variable not an NSImage. I have also tried various other ways to get this done, but all are unsuccessful either due to compiler or runtime error. Can someone help me with this? I will eventually need to load some PNG files in the same way (so it would be nice to have a consistent technique for both). And if you know of an easier / simpler way to accomplish what I am trying to do (i.e., get the images into a two-dimensional array), rather than using NSBitmapImageRep, then please let me know! And by the way, I know the path is valid (confirmed with fileExistsAtPath) -- and the filename in outLabel is a file with .jpg extension. Thanks for any help!

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  • Help with java executors: wait for task termination.

    - by Raffo
    I need to submit a number of task and then wait for them until all results are available. Each of them adds a String to a Vector (that is synchronized by default). Then I need to start a new task for each result in the Vector but I need to do this only when all the previous tasks have stopped doing their job. I want to use Java Executor, in particular I tried using Executors.newFixedThreadPool(100) in order to use a fixed number of thread (I have a variable number of task that can be 10 or 500) but I'm new with executors and I don't know how to wait for task termination. This is something like a pseudocode of what my program needs to do: EecutorService e = Executors.newFixedThreadPool(100); while(true){ /*do something*/ for(...){ <start task> } <wait for all task termination> for each String in result{ <start task> } <wait for all task termination> } I can't do a e.shutdown because I'm in a while(true) and I need to reuse the executorService... Can you help me? Can you suggest me a guide/book about java executors??

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  • Applying policy based design question

    - by Arthur
    I've not read the Modern C++ Design book but have found the idea of behavior injection through templates interesting. I am now trying to apply it myself. I have a class that has a logger that I thought could be injected as a policy. The logger has a log() method which takes an std::string or std::wstring depending on its policy: // basic_logger.hpp template<class String> class basic_logger { public: typedef String string_type; void log(const string_type & s) { ... } }; typedef basic_logger<std::string> logger; typedef basic_logger<std::wstring> wlogger; // reader.hpp template<class Logger = logger> class reader { public: typedef Logger logger_type; void read() { _logger.log("Reading..."); } private: logger_type _logger; }; Now the questing is, should the reader take a Logger as an argument, like above, or should it take a String and then instantiate a basic_logger as an instance variable? Like so: template<class String> class reader { public: typedef String string_type; typedef basic_logger<string_type> logger_type; // ... private: logger_type _logger; }; What is the right way to go?

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  • NSURLConnection and empty post variables

    - by SooDesuNe
    I'm at my wits end with this one, because I've used very similar code in the past, and it worked just fine. The following code results in empty $_POST variables on the server. I verified this with: file_put_contents('log_file_name', "log: ".$word, FILE_APPEND); the only contents of log_file_name was "log: " I then verified the PHP with a simple HTML form. It performed as expected. The Objective-C: NSString *word = "this_word_gets_lost"; NSString *myRequestString = [NSString stringWithFormat:@"word=%@", word]; [self postAsynchronousPHPRequest:myRequestString toPage:@"http://www.mysite.com/mypage.php" delegate:nil]; } -(void) postAsynchronousPHPRequest:(NSString*)request toPage:(NSString*)URL delegate:(id)delegate{ NSData *requestData = [ NSData dataWithBytes: [ request UTF8String ] length: [ request length ] ]; NSMutableURLRequest *URLrequest = [ [ NSMutableURLRequest alloc ] initWithURL: [ NSURL URLWithString: URL ] ]; [ URLrequest setHTTPMethod: @"POST" ]; [ URLrequest setHTTPBody: requestData ]; [ NSURLConnection connectionWithRequest:URLrequest delegate:delegate]; [URLrequest release]; } The PHP: $word = $_POST['word']; file_put_contents('log_file_name', "log: ".$word, FILE_APPEND); What am I doing wrong in the Objective-C that would cause the $_POST variable to be empty on the server?

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  • How to set up django-admin.py on windos vista?

    - by shin
    I manage to install Django after some struggles by using setup.py install on Windows Vista Now I tried to use django-admin.py but it is not working. According to this document, http://docs.djangoproject.com/en/dev/ref/django-admin/ The django-admin.py script should be on your system path if you installed Django via its setup.py utility. If it’s not on your path, ... For Windows users, who do not have symlinking functionality available, you can copy django-admin.py to a location on your existing path or edit the PATH settings (under Settings - Control Panel - System - Advanced - Environment...) to point to its installed location. I checked ComputerpropertiesEnvironment Variables, but path to django-admin.py is not in anywhere. So I added C:\Python25\Lib\site-packages\django\bin which is the folder of django-admin.py in User variables for shin Variable PATH, Value C:\Program Files\Google\google_appengine\;C:\Python25\Lib\site-packages\django\bin\ Am I supposed to add to System variables?? But it still does not work. Could anyone tell me how to add the Path in Environment Variables please? Thanks in advance.

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  • Editing a .class file directly, playing around with opcodes

    - by echox
    Hi, today I just tried to play a little bit around with the opcodes in compiled java class file. After inserting iinc 1,1 the java virtual machine responds with: Exception in thread "main" java.lang.ClassFormatError: Truncated class file at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632) at java.lang.ClassLoader.defineClass(ClassLoader.java:616) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141) at java.net.URLClassLoader.defineClass(URLClassLoader.java:283) at java.net.URLClassLoader.access$000(URLClassLoader.java:58) at java.net.URLClassLoader$1.run(URLClassLoader.java:197) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:248) Could not find the main class: Test. Program will exit. This is my example source code: public class Test { public static void main(String[] args) { int i = 5; i++; i++; i++; System.out.println("Number: " + i + "\n"); } } The opcode for an increment is 0x84 + 2 bytes for operands. There's only one section in the resulting class file, which contains 0x84: [..] 8401 0184 0101 8401 01[..] So I would translate this as: iinc 1,1 iinc 1,1 iinc 1,1 corresponding to my i++; i++; i++; I then tried to append just 840101 to increment the variable once more, but that didn't work and resulted in the ClassFormatError. Is there anything like a checksum for the class file? I looked up the format of a classfile in http://java.sun.com/docs/books/jvms/second_edition/html/ClassFile.doc.html but could not find anything which points out to some kind of bytes_of_classfile or something. I also don't understand why the error is "Truncated Class File", because I did append something :-) I know its not a good idea to edit class files directly, but I'm just interested on the VM internals here.

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  • javascript - How to pass an argument in a function call?

    - by Fernando SBS
    function rp_marcadesmarcaFarm(valor) { FM_log(3, "marcadesmarcaFarm called = "+valor); for (i = 0; i < farmList.length; i++) { var arr = farmList[i].split("|"); var xy = arr[0].split(","); var fvillageId = xy2id(parseInt(xy[0]), parseInt(xy[1])); GM_setValue("farmAtivada_"+suffixLocal+fvillageId, valor); GM_setValue("farmAtivada_"+suffixLocal+i, valor); }; reloadFarmTable(); }; function createLinkButton(text, title, jsFunction, value) { var button = dom.cn("a"); button.href = "javascript:void(0)"; button.innerHTML = text; button.title = title; if (jsFunction != null) { button.addEventListener('click', jsFunction, false); } return button; } createLinkButton("X", T('CHECKFARM_M'), rp_marcadesmarcaFarm(true)); apparently the last argument (rp_marcadesmarcaFarm(true)) when invoking the createLinkButton is not working. If I change to: createLinkButton("X", T('CHECKFARM_M'), rp_marcadesmarcaFarm); it works. So how can I pass the (true) variable to the third argument of createLinkButton?

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  • Algorithm(s) for rearranging simple symbolic algebraic expressions

    - by Gabe Johnson
    Hi, I would like to know if there is a straightforward algorithm for rearranging simple symbolic algebraic expressions. Ideally I would like to be able to rewrite any such expression with one variable alone on the left hand side. For example, given the input: m = (x + y) / 2 ... I would like to be able to ask about x in terms of m and y, or y in terms of x and m, and get these: x = 2*m - y y = 2*m - x Of course we've all done this algorithm on paper for years. But I was wondering if there was a name for it. It seems simple enough but if somebody has already cataloged the various "gotchas" it would make life easier. For my purposes I won't need it to handle quadratics. (And yes, CAS systems do this, and yes I know I could just use them as a library. I would like to avoid such a dependency in my application. I really would just like to know if there are named algorithms for approaching this problem.)

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  • check whether mmap'ed address is correct

    - by reddot
    I'm writing a high-loaded daemon that should be run on the FreeBSD 8.0 and on Linux as well. The main purpose of daemon is to pass files that are requested by their identifier. Identifier is converted into local filename/file size via request to db. And then I use sequential mmap() calls to pass file blocks with send(). However sometimes there are mismatch of filesize in db and filesize on filesystem (realsize < size in db). In this situation I've sent all real data blocks and when next data block is mapped -- mmap returns no errors, just usual address (I've checked errno variable also, it's equal to zero after mmap). And when daemon tries to send this block it gets Segmentation Fault. (This behaviour is guarantedly issued on FreeBSD 8.0 amd64) I was using safe check before open to ensure size with stat() call. However real life shows to me that segfault still can be raised in rare situtaions. So, my question is there a way to check whether pointer is accessible before dereferencing it? When I've opened core in gdb, gdb says that given address is out of bound. Probably there is another solution somebody can propose.

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  • Delphi App has "No Debug Info" when Debugging

    - by James L.
    We have built an application that uses packages and components. When we debug the application, the "Event Log" in the IDE often shows the our BPLs are being loaded without debug information ("No Debug Info"). This doesn't make sense because all our packages and EXEs are built with debug. _(each project) | Options | Compiling_ [ x ] Assertions [ x ] Debug information [ x ] Local symbols Symbol reference info = "Reference info" [ ] Use debug .dcus [ x ] Use imported data references _(each project) | Options | Linking_ [ x ] Debug information Map file = Detailed We have 4 projects, all built with runtime pacakges: Core.bpl Components.bpl Plugin.bpl (uses both #1 & #2) MainApp.exe (uses #1) Problems Observed 1) Many times when we debug, the Components.bpl is loaded with debug info, but all values in the "Local Variables" window are blank. If you hover your mouse over a variable in the code, there is no popup, and Evaluate window also shows nothing (the "Result" pane is always blank). 2) Sometimes the Event Log shows "No Debug Info" for various BPLs. For instance, if we activate the Plugin.bpl project and set it's Run | Parameter's Host Application to be the MainApp.exe, and then press F9, all modules seems to load with "Has Debug Info" except for the Plugin.bpl module. When it loads, the Event Log shows "No Debug Info". However, if we close the app and immediately press F9, it will run it again without recompiling anything and this time Plugin.bpl is loaded with debug ("Has Debug Info"). Questions 1) What would cause the "Local Variables" window to not display the values? 2) Why are BPLs sometimes loaded without debug info when the BPL was complied with debug and all the debug files (dcu, map, etc.) are available?

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  • Generic Singleton Façade design pattern

    - by Paul
    Hi I try write singleton façade pattern with generics. I have one problem, how can I call method from generic variable. Something like this: T1 t1 = new T1(); //call method from t1 t1.Method(); In method SingletonFasadeMethod I have compile error: Error 1 'T1' does not contain a definition for 'Method' and no extension method 'Method' accepting a first argument of type 'T1' could be found (are you missing a using directive or an assembly reference?) Any advace? Thank, I am beginner in C#. All code is here: namespace GenericSingletonFasade { public interface IMyInterface { string Method(); } internal class ClassA : IMyInterface { public string Method() { return " Calling MethodA "; } } internal class ClassB : IMyInterface { public string Method() { return " Calling MethodB "; } } internal class ClassC : IMyInterface { public string Method() { return "Calling MethodC"; } } internal class ClassD : IMyInterface { public string Method() { return "Calling MethodD"; } } public class SingletonFasade<T1,T2,T3> where T1 : class,new() where T2 : class,new() where T3 : class,new() { private static T1 t1; private static T2 t2; private static T3 t3; private SingletonFasade() { t1 = new T1(); t2 = new T2(); t3 = new T3(); } class SingletonCreator { static SingletonCreator() { } internal static readonly SingletonFasade<T1,T2,T3> uniqueInstace = new SingletonFasade<T1,T2,T3>(); } public static SingletonFasade<T1,T2,T3> UniqueInstace { get { return SingletonCreator.uniqueInstace; } } public string SingletonFasadeMethod() { //Problem is here return t1.Method() + t2.Method() + t3.Method(); } } } I use this for my problem. public class SingletonFasade<T1, T2, T3> where T1 : class, IMyInterface, new() where T2 : class, IMyInterface, new() where T3 : class, IMyInterface, new() {//...} Is any solution without Interfaces ??

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  • Javascript string replace with calculations

    - by Chris
    Is there a way to resolve mathematical expressions in strings in javascript? For example, suppose I want to produce the string "Tom has 2 apples, Lucy has 3 apples. Together they have 5 apples" but I want to be able to substitute in the variables. I can do this with a string replacement: string = "Tom has X apples, Lucy has Y apples. Together they have Z apples"; string2 = string.replace(/X/, '2').replace(/Y/, '3').replace(/Z/, '5'); However, it would be better if, instead of having a variable Z, I could use X+Y. Now, I could also do a string replace for X+Y and replace it with the correct value, but that would become messy when trying to deal with all the possible in-string calculations I might want to do. I suppose I'm looking for a way to achieve this: string = "Something [X], something [Y]. Something [(X+Y^2)/5X]"; And for the [_] parts to be understood as expressions to be resolved before substituting back into the string. Thanks for your help.

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  • Re-tweets and replies with JTwitter

    - by Samuh
    I have not used Twitter enough to become familiar with its terminology or the way it works, so please help me in understanding the problem I have at hand. I am getting last 20 status updates posted by some Twitter user via RSS feed, the feed XML is parsed and the statuses are displayed in a ListView. Which means that I have the original tweet in a String variable(row of ListView). When I click a ListView item, I get the option of "Re-tweeting" and "post reply". As, I understand it, when re-tweeting I will have to just update my *status* as: RT @orig-poster <original tweet> and when posting a reply I will have to just update my status as: @orig-poster <my tweet> I skimmed through the JavaDocs of the Jwitter library(Twitter class) and found a setStatus(String) method. I dont think I will have to make use of retweet() or reply() functions of the Twitter class in JTwitter library. Is my understanding correct? Please correct me if I am wrong here or missing anything. Thanks!

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  • JSF 2.0 Dynamic Views

    - by Robe Eleckers
    Hello, I'm working on a web project which uses JSF 2.0, PrimeFaces and PrettyFaces as main frameworks / libraries. The pages have the following (common) structure: Header, Content, Footer. Header: The Header always contains the same menu. This menu is a custom component, which generates a recursive html <ul><li> list containing <a href="url"> html links, this is all rendered with a custom renderer. The link looks like 'domain.com/website/datatable.xhtml?ref=2'. Where the ref=2 used to load the correct content from the database. I use prettyfaces to store this request value in a backingbean. Question 1: Is it ok to render the <a href> links myself, or should I better add an HTMLCommandLink from my UIComponent and render that in the encodeBegin/End? Question 2: I think passing variables like this is not really the JSF 2.0 style, how to do this in a better way? Content: The content contains dynamic data. It can be a (primefaces) datatable, build with dynamic data from the database. It can also be a text page, also loaded from the database. Or a series of graphs. You got the point, it's dynamic. The content is based on the link pressed in the header menu. If the content is of type datatable, then I put the ref=2 variable to a DataTableBean (via prettyfaces), which then loads the correct datatable from the database. If the content is of type chart, I'll put it on the ChartBean. Question 3: Is this a normal setup? Ideally I would like to update my content via Ajax. I hope it's clear :)

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  • How to output KML by GAE

    - by Niklas R
    Hi I use KML for a google map where entities have a geopt.db coordinate and soft memory limit was exceeded with 213.465 MB after servicing 1 requests total. The log says /list.kml 200 13130ms 10211cpu_ms 4238api_cpu_ms The file list.kml which outputs about 455,7 KB is a template as follows <?xml version="1.0" encoding="UTF-8"?><kml xmlns="http:// www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:atom="http:// www.w3.org/2005/Atom"> <Document>{% for a in list %} <Placemark> <name> </name> <description> <![CDATA[<a href="http://{{host}}/{{a.key.id}}"> {{ a.title }} </a> <br/>{{a.text}}]]> </description> <Style> <IconStyle> <Icon> <href> http://www.google.com/intl/en_us/mapfiles/ms/icons/green-dot.png </href> </Icon> </IconStyle> </Style> <Point> <coordinates> {{a.geopt.lon|floatformat:2}},{{a.geopt.lat|floatformat:2}} </coordinates> </Point> </Placemark> {% endfor %} </Document> </kml> Is there a memory leak in the template or the python that passes the list variable? Can I improve using other template engine or other framework than default? Is kmz compression a good idea in this case? Thanks in advance for any suggestion where or how to change the code.

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  • How do I DYNAMICALLY cast in C# and return for a property

    - by ken-forslund
    I've already read threads on the topic, but can't find a solution that fits. I'm working on a drop-down list that takes an enum and uses that to populate itself. i found a VB.NET one. During the porting process, I discovered that it uses DirectCast() to set the type as it returns the SelectedValue. See the original VB here: http://jeffhandley.com/archive/2008/01/27/enum-list-dropdown-control.aspx the gist is, the control has Type _enumType; //gets set when the datasource is set and is the type of the specific enum The SelectedValue property kind of looks like (remember, it doesn't work): public Enum SelectedValue //Shadows Property { get { // Get the value from the request to allow for disabled viewstate string RequestValue = this.Page.Request.Params[this.UniqueID]; return Enum.Parse(_enumType, RequestValue, true) as _enumType; } set { base.SelectedValue = value.ToString(); } } Now this touches on a core point that I think was missed in the other discussions. In darn near every example, folks argued that DirectCast wasn't needed, because in every example, they statically defined the type. That's not the case here. As the programmer of the control, I don't know the type. Therefore, I can't cast it. Additionally, the following examples of lines won't compile because c# casting doesn't accept a variable. Whereas VB's CType and DirectCast can accept Type T as a function parameter: return Enum.Parse(_enumType, RequestValue, true); or return Enum.Parse(_enumType, RequestValue, true) as _enumType; or return (_enumType)Enum.Parse(_enumType, RequestValue, true) ; or return Convert.ChangeType(Enum.Parse(_enumType, RequestValue, true), _enumType); or return CastTo<_enumType>(Enum.Parse(_enumType, RequestValue, true)); So, any ideas on a solution? What's the .NET 3.5 best way to resolve this?

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  • MEF GetExports<T, TMetaDataView> returning nothing with AllowMultiple = True

    - by sohum
    I don't understand MEF very well, so hopefully this is a simple fix of how I think it works. I'm trying to use MEF to get some information about a class and how it should be used. I'm using the Metadata options to try to achieve this. My interfaces and attribute looks like this: public interface IMyInterface { } public interface IMyInterfaceInfo { Type SomeProperty1 { get; } double SomeProperty2 { get; } string SomeProperty3 { get; } } [MetadataAttribute] [AttributeUsage(AttributeTargets.Class, AllowMultiple = true)] public class ExportMyInterfaceAttribute : ExportAttribute, IMyInterfaceInfo { public ExportMyInterfaceAttribute(Type someProperty1, double someProperty2, string someProperty3) : base(typeof(IMyInterface)) { SomeProperty1 = someProperty1; SomeProperty2 = someProperty2; SomeProperty3 = someProperty3; } public Type SomeProperty1 { get; set; } public double SomeProperty2 { get; set; } public string SomeProperty3 { get; set; } } The class that is decorated with the attribute looks like this: [ExportMyInterface(typeof(string), 0.1, "whoo data!")] [ExportMyInterface(typeof(int), 0.4, "asdfasdf!!")] public class DecoratedClass : IMyInterface { } The method that is trying to use the import looks like this: private void SomeFunction() { // CompositionContainer is an instance of CompositionContainer var myExports = CompositionContainer.GetExports<IMyInterface, IMyInterfaceInfo>(); } In my case myExports is always empty. In my CompositionContainer, I have a Part in my catalog that has two ExportDefinitions, both with the following ContractName: "MyNamespace.IMyInterface". The Metadata is also loaded correctly per my exports. If I remove the AllowMultiple setter and only include one exported attribute, the myExports variable now has the single export with its loaded metadata. What am I doing wrong?

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  • pointer-to-pointer of derived class in multiple inheritance

    - by Abdul jalil
    i have 3 classes A,B and C. C is derived from A and B. i get pointer to pointer of class C and cast to A** , and B ** , the variable that hold the the B** has the address of A** in my example B ** BdoublePtr hold the address of A** .i am using the following code #include "conio.h" #include "stdio.h" #include "string.h" class A{ public: A() { strA=new char[30]; strcpy(strA,"class A"); } char *strA; }; class B { public: B() { strB=new char[30]; strcpy(strB,"class B"); } char *strB; }; class C :public A, public B { public: C() { strC=new char[30]; strcpy(strC,"class C"); } char *strC; }; int main(void) { C* ptrC=new C(); A * Aptr=(A*)ptrC; printf("\n class A value : %s",Aptr-strA); B * Bptr=(B*)ptrC; printf("\n class B value :%s",Bptr-strB); printf("\n\nnow with double pointer "); A ** AdoublePtr=(A **)&ptrC; Aptr=AdoublePtr; printf("\n class A value : %s",Aptr-strA); B * BdoublePtr=(B **)&ptrC; Bptr=*BdoublePtr; printf("\n class B value : %s",Bptr-strB); getch(); return 0; }

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  • Have I taken a wrong path in programming by being excessively worried about code elegance and style?

    - by Ygam
    I am in a major stump right now. I am a BSIT graduate, but I only started actual programming less than a year ago. I observed that I have the following attitude in programming: I tend to be more of a purist, scorning unelegant approaches to solving problems using code I tend to look at anything in a large scale, planning everything before I start coding, either in simple flowcharts or complex UML charts I have a really strong impulse on refactoring my code, even if I miss deadlines or prolong development times I am obsessed with good directory structures, file naming conventions, class, method, and variable naming conventions I tend to always want to study something new, even, as I said, at the cost of missing deadlines I tend to see software development as something to engineer, to architect; that is, seeing how things relate to each other and how blocks of code can interact (I am a huge fan of loose coupling) i.e the OOP thinking I tend to combine OOP and procedural coding whenever I see fit I want my code to execute fast (thus the elegant approaches and refactoring) This bothers me because I see my colleagues doing much better the other way around (aside from the fact that they started programming since our first year in college). By the other way around I mean, they fire up coding, gets the job done much faster because they don't have to really look at how clean their codes are or how elegant their algorithms are, they don't bother with OOP however big their projects are, they mostly use web APIs, piece them together and voila! Working code! CLients are happy, they get paid fast, at the expense of a really unmaintainable or hard-to-read code that lacks structure and conventions, or slow executions of certain actions (which the common reasoning against would be that internet connections are much faster these days, hardware is more powerful). The excuse I often receive is clients don't care about how you write the code, but they do care about how long you deliver it. If it works then all is good. Now, did my "purist" approach to programming may have been the wrong way to start programming? Should I just dump these purist concepts and just code the hell up because I have seen it: clients don't really care how beautifully coded it is?

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  • Inheritance of closure objects and overriding of methods

    - by bobikk
    I need to extend a class, which is encapsulated in a closure. This base class is following: var PageController = (function(){ // private static variable var _current_view; return function(request, new_view) { ... // priveleged public function, which has access to the _current_view this.execute = function() { alert("PageController::execute"); } } })(); Inheritance is realised using the following function: function extend(subClass, superClass){ var F = function(){ }; F.prototype = superClass.prototype; subClass.prototype = new F(); subClass.prototype.constructor = subClass; subClass.superclass = superClass.prototype; StartController.cache = ''; if (superClass.prototype.constructor == Object.prototype.constructor) { superClass.prototype.constructor = superClass; } } I subclass the PageController: var StartController = function(request){ // calling the constructor of the super class StartController.superclass.constructor.call(this, request, 'start-view'); } // extending the objects extend(StartController, PageController); // overriding the PageController::execute StartController.prototype.execute = function() { alert('StartController::execute'); } Inheritance is working. I can call every PageController's method from StartController's instance. However, method overriding doesn't work: var startCont = new StartController(); startCont.execute(); alerts "PageController::execute". How should I override this method?

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  • Java: Efficiency of the readLine method of the BufferedReader and possible alternatives

    - by Luhar
    We are working to reduce the latency and increase the performance of a process written in Java that consumes data (xml strings) from a socket via the readLine() method of the BufferedReader class. The data is delimited by the end of line separater (\n), and each line can be of a variable length (6KBits - 32KBits). Our code looks like: Socket sock = connection; InputStream in = sock.getInputStream(); BufferedReader inputReader = new BufferedReader(new InputStreamReader(in)); ... do { String input = inputReader.readLine(); // Executor call to parse the input thread in a seperate thread }while(true) So I have a couple of questions: Will the inputReader.readLine() method return as soon as it hits the \n character or will it wait till the buffer is full? Is there a faster of picking up data from the socket than using a BufferedReader? What happens when the size of the input string is smaller than the size of the Socket's receive buffer? What happens when the size of the input string is bigger than the size of the Socket's receive buffer? I am getting to grips (slowly) with Java's IO libraries, so any pointers are much appreciated. Thank you!

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  • Codeigniter: db data in controller

    - by Kevin Brown
    I'm confused about what to do... I'm working on a user's page where they can view certain things only if their supervisor has given them "money" or "credits". I need a simple way to get the person that is their supervisor by doing something like: $data['employer'] = $this->home_model->getEmployees(array('user_id'=>$manager_id)); Basically, get the user information about a person who's user_id matches the manager_id of the currently logged in member. I don't know how to set the variable $manager_id. Additional Information: The current user has an id, and a manager_id. I need the id of the manager. So, I need to grab the manager_id of the logged-in user and find the manager who's user_id is that of the manager_id. What's the process to do this? I can get each individually, but I don't know how to use one to get the other... I know it is confusing, but I'm confused! Thanks for the help!

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  • Problems compiling libjingle/gtk+-2.0 for Mac OS X

    - by mindthief
    Hi All, I'm trying to compile libjingle on Mac OSX Snow Leopard. The INSTALL file said to './configure', 'make' and 'make install', as usual. But make fails for me. Initially it gave some messages indicating that I didn't have pkg-config installed (I guess OSX doesn't come with it installed?), so I downloaded pkg-config from http://pkgconfig.freedesktop.org/releases/ Now I get this message: Package gtk+-2.0 was not found in the pkg-config search path. Perhaps you should add the directory containing `gtk+-2.0.pc' to the PKG_CONFIG_PATH environment variable No package 'gtk+-2.0' found I tried to install gtk by using the script at SourceForge: http://sourceforge.net/projects/gtk-osx/ (this is the website pointed to by the gtk website) Running the script didn't really seem to do anything, here is the output: $./gtk-osx-build-setup.sh Checking out jhbuild (2.27.3) from git... From git://git.gnome.org/jhbuild * tag 2.27.3 -> FETCH_HEAD Installing jhbuild... Installing jhbuild configuration... Installing gtk-osx moduleset files... Done. $ And I still get that error message about "Package gtk+-2.0 not found" while make-ing libjingle. Help will be appreciated, 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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