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  • Shared(Static) classes with events in C#

    - by diamandiev
    Here is an example of what i would do in vb: Public Class Class1 Public Shared WithEvents Something As New EventClass Public Shared Sub DoStuff() Handles Something.Test End Sub End Class Public Class EventClass Public Event Test() End Class Now how do i do this in c#. I know there is not handles clause in c# so i need some function that is called and assign the event handlers there. However since its a shared class there is no constructor i must put it somewhere outside of a function. Any ideas?

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  • bad file descriptor with close() socket (c++)

    - by user321246
    hi everybody! I'm running out of file descriptors when my program can't connect another host. The close() system call doesn't work, the number of open sockets increases. I can se it with cat /proc/sys/fs/file-nr Print from console: connect: No route to host close: Bad file descriptor connect: No route to host close: Bad file descriptor .. Code: #include <stdio.h> #include <stdlib.h> #include <sys/socket.h> #include <netinet/in.h> #include <netdb.h> #include <string.h> #include <iostream> using namespace std; #define PORT 1238 #define MESSAGE "Yow!!! Are we having fun yet?!?" #define SERVERHOST "192.168.9.101" void write_to_server (int filedes) { int nbytes; nbytes = write (filedes, MESSAGE, strlen (MESSAGE) + 1); if (nbytes < 0) { perror ("write"); } } void init_sockaddr (struct sockaddr_in *name, const char *hostname, uint16_t port) { struct hostent *hostinfo; name->sin_family = AF_INET; name->sin_port = htons (port); hostinfo = gethostbyname (hostname); if (hostinfo == NULL) { fprintf (stderr, "Unknown host %s.\n", hostname); } name->sin_addr = *(struct in_addr *) hostinfo->h_addr; } int main() { for (;;) { sleep(1); int sock; struct sockaddr_in servername; /* Create the socket. */ sock = socket (PF_INET, SOCK_STREAM, 0); if (sock < 0) { perror ("socket (client)"); } /* Connect to the server. */ init_sockaddr (&servername, SERVERHOST, PORT); if (0 > connect (sock, (struct sockaddr *) &servername, sizeof (servername))) { perror ("connect"); sock = -1; } /* Send data to the server. */ if (sock > -1) write_to_server (sock); if (close (sock) != 0) perror("close"); } return 0; }

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  • using Inheritence with GUI (graphical user interfaces) in Java

    - by maya
    hi everyone, I work on inheritence with GUI (graphical user interfaces) let me explain for example I made super class which is vehicle and the subclass is car, so the code to make inheritence will be public class Car extends Vehicle then I want to build the class Car as JFrame like public class Car JFrame implements ActionListener { so the problem is that I couldn't put both codes in the same class, and I need to do that. anyone help me. thanks in advance I wish that the question would be clear

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  • How to startactivityforresult in tab child of TabHost

    - by user541383
    I have TabHost with tab child like this: tabHost.addTab(tabHost.newTabSpec("web") .setIndicator("web") .setContent(new Intent(this, webview.class))); In WebView class, I startactivityforresult: startActivityForResult(new Intent(Webview.this,EventManage.class),GET_CODE); In Eventmanage class, I set result but can not capture result in webview class. Anybody can help me with this problem?

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  • Dynamic Dispatch without Virtual Functions

    - by Kristopher Johnson
    I've got some legacy code that, instead of virtual functions, uses a kind field to do dynamic dispatch. It looks something like this: // Base struct shared by all subtypes // Plain-old data; can't use virtual functions struct POD { int kind; int GetFoo(); int GetBar(); int GetBaz(); int GetXyzzy(); }; enum Kind { Kind_Derived1, Kind_Derived2, Kind_Derived3 }; struct Derived1: POD { Derived1(): kind(Kind_Derived1) {} int GetFoo(); int GetBar(); int GetBaz(); int GetXyzzy(); // plus other type-specific data and function members }; struct Derived2: POD { Derived2(): kind(Kind_Derived2) {} int GetFoo(); int GetBar(); int GetBaz(); int GetXyzzy(); // plus other type-specific data and function members }; struct Derived3: POD { Derived3(): kind(Kind_Derived3) {} int GetFoo(); int GetBar(); int GetBaz(); int GetXyzzy(); // plus other type-specific data and function members }; and then the POD class's function members are implemented like this: int POD::GetFoo() { // Call kind-specific function switch (kind) { case Kind_Derived1: { Derived1 *pDerived1 = static_cast<Derived1*>(this); return pDerived1->GetFoo(); } case Kind_Derived2: { Derived2 *pDerived2 = static_cast<Derived2*>(this); return pDerived2->GetFoo(); } case Kind_Derived3: { Derived3 *pDerived3 = static_cast<Derived3*>(this); return pDerived3->GetFoo(); } default: throw UnknownKindException(kind, "GetFoo"); } } POD::GetBar(), POD::GetBaz(), POD::GetXyzzy(), and other members are implemented similarly. This example is simplified. The actual code has about a dozen different subtypes of POD, and a couple dozen methods. New subtypes of POD and new methods are added pretty frequently, and so every time we do that, we have to update all these switch statements. The typical way to handle this would be to declare the function members virtual in the POD class, but we can't do that because the objects reside in shared memory. There is a lot of code that depends on these structs being plain-old-data, so even if I could figure out some way to have virtual functions in shared-memory objects, I wouldn't want to do that. So, I'm looking for suggestions as to the best way to clean this up so that all the knowledge of how to call the subtype methods is centralized in one place, rather than scattered among a couple dozen switch statements in a couple dozen functions. What occurs to me is that I can create some sort of adapter class that wraps a POD and uses templates to minimize the redundancy. But before I start down that path, I'd like to know how others have dealt with this.

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  • Specializing a template on a lambda in C++0x

    - by Tony A.
    I've written a traits class that lets me extract information about the arguments and type of a function or function object in C++0x (tested with gcc 4.5.0). The general case handles function objects: template <typename F> struct function_traits { template <typename R, typename... A> struct _internal { }; template <typename R, typename... A> struct _internal<R (F::*)(A...)> { // ... }; typedef typename _internal<decltype(&F::operator())>::<<nested types go here>>; }; Then I have a specialization for plain functions at global scope: template <typename R, typename... A> struct function_traits<R (*)(A...)> { // ... }; This works fine, I can pass a function into the template or a function object and it works properly: template <typename F> void foo(F f) { typename function_traits<F>::whatever ...; } int f(int x) { ... } foo(f); What if, instead of passing a function or function object into foo, I want to pass a lambda expression? foo([](int x) { ... }); The problem here is that neither specialization of function_traits<> applies. The C++0x draft says that the type of the expression is a "unique, unnamed, non-union class type". Demangling the result of calling typeid(...).name() on the expression gives me what appears to be gcc's internal naming convention for the lambda, main::{lambda(int)#1}, not something that syntactically represents a C++ typename. In short, is there anything I can put into the template here: template <typename R, typename... A> struct function_traits<????> { ... } that will allow this traits class to accept a lambda expression?

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  • Retrieving the Selected value dynamically in JQuery

    - by Chakradhar
    i have this html, this is generated dynamically based on question number <fieldset id="selectfield"> <label class="select">What ur is Profession? </label> <br> <div class="ui-select"><a href="#" role="button" id="72+_select-button" aria-haspopup="true" aria-owns="72+_select-menu" data-theme="c" class="ui-btn ui-btn-icon-right ui-btn-corner-all ui-shadow ui-btn-hover-c ui-btn-up-c"><span class="ui-btn-inner ui-btn-corner-all" aria-hidden="true"><span class="ui-btn-text">Business</span><span class="ui-icon ui-icon-arrow-d ui-icon-shadow"></span></span></a> <select name="selectedObjects" id="72+_select" data-native-menu="false" tabindex="-1"> <option value="-1">--Select--</option> <option value="769">Salaried</option> <option selected="selected" value="770">Business</option> <option value="771">Self Emp</option> </select></div> </fieldset> click button is <div data-theme="c" class="ui-btn ui-btn-corner-all ui-shadow ui-btn-hover-c ui-btn-up-c" aria-disabled="false"><span class="ui-btn-inner ui-btn-corner-all" aria-hidden="true"><span class="ui-btn-text">Next</span></span> <input type="submit" id="72+_b" onclick="return SaveDropDown(this);" value="Next" class="ui-btn-hidden" aria-disabled="false"> </div> i have written this JS in SaveDropDown(this) function SaveDropDown(button) { var fieldsetName = getQuestionName(button.id)+'+_select'; var select = $(fieldsetName +"option:selected").val(); return false; } the questionname function is function getQuestionName(buttonid) { var splitstr = buttonid.split('+'); var fieldsetName = '#' + splitstr[0]; return fieldsetName; } but its returning the undefined how do i retrieve the select value dynamically. any help is appreciated.

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  • Object responsibilities - list and item

    - by Mark Tyler
    My question is more like a theoretical. Say you have an object, that represents the list of something (articles, pages, accounts etc.) class ObjCollection You have a class, that represents a specific item in collection: class objItem I have a problem thinking of a basic responsibilities of each object. Which class is responsible for creating a new objItem? Which class is responsible for deleting a objItem? Should it delete itself as a method?

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  • Singleton with eager initialization

    - by jesper
    I have class X that takes much time to initialize itself. I want to make that class singleton and force its creation when rails application starts. I've made the singleton: class X @@instance = nil def self.instance if @@instance.nil? @@instance = X.new puts 'CREATING' end return @@instance end private_class_method :new end The problem is that every time I use this class I see 'CREATING' in logs. I've tried to put creation of class in initializers directory but it doesn't work either.

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  • Repeating a object that only occurs couple of times and has different values with htmlagilitypack c#.

    - by dtd
    I have a problem I cant seem to solve here. Lets say I have some html like beneth here that I want to parse. All this html is within one list on the page. And the names repeat themself like in the example I wrote. <li class = "seperator"> a date </li> <li class = "lol"> some text </li> <li class = "lol"> some text </li> <li class = "lol"> some text </li> <li class = "seperator"> a new date </li> <li class = "lol"> some text </li> <li class = "seperator"> a nother new date </li> <li class = "lol"> some text </li> <li class = "lol"> some text </li> I did manage to use htmlagility pack to parse every li object seperate, and almost formating it how I want. My print atm looks something like this: "a date" "some text" "some text" "some text" "some text" "a new date" "some text" "a nother new date " "some text" "some text" "some text" What I want to achive: "a date" "some text" "a date" "some text" "a date" "some text" "a date" "some text" "a new date" "some text" "a nother new date " "some text" "a nother new date " "some text" "a nother new date " "some text" But the problem is that beneath every seperator, the count of every lol object may vary. So one day, the webpage may have one lol object beneth date 1, and the next day it may have 10 lol objects. So I am woundering if there is an smart/easy way to somehow count the number of lol objects in between the seperators. Or if there is another way to figure this out? Within for example htmlagilitypack. And yes, I need the correct date in front of every lol object, not just infront the first one. This would have been a pice of cake if the seperator class would have ended beneath the last lol object, but sadly that is not the case... I dont think that I need to paste my code here, but basicly what I do is to parse the page, extract the seperators and lol objects and add them to a list, where I split them up to seperator and lol objects. Then I print it out to a file and since the seperator only occure 3 times(in the example) I will only get out 3 seperate dates.

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  • Patterns for dynamic CMS components (event driven?)

    - by CitrusTree
    Sorry my title is not great, this is my first real punt at moving 100% to OO as I've been procedural for more years than I can remember. I'm finding it hard to understand if what I'm trying to do is possible. Depending on people's thoughts on the 2 following points, I'll go down that route. The CMS I'm putting together is quote small, however focuses very much on different types of content. I could easily use Drupal which I'm very comfortable with, but I want to give myself a really good reasons to move myself into design patterns / OO-PHP 1) I have created a base 'content' class which I wish to be able to extend to handle different types of content. The base class, for example, handles HTML content, and extensions might handle XML or PDF output instead. On the other hand, at some point I may wish to extend the base class for a given project completely. I.e. if class 'content-v2' extended class 'content' for that site, any calls to that class should actually call 'content-v2' instead. Is that possible? If the code instantiates an object of type 'content' - I actually want it to instantiate one of type 'content-v2'... I can see how to do it using inheritance, but that appears to involve referring to the class explicitly, I can't see how to link the class I want it to use instead dynamically. 2) Secondly, the way I'm building this at the moment is horrible, I'm not happy with it. It feels very linear indeed - i.e. get session details get content build navigation theme page publish. To do this all the objects are called 1-by-1 which is all very static. I'd like it to be more dynamic so that I can add to it at a later date (very closely related to first question). Is there a way that instead of my orchestrator class calling all the other classes 1-by-1, then building the whole thing up at the end, that instead each of the other classes can 'listen' for specific events, then at the applicable point jump in and do their but? That way the orchestrator class would not need to know what other classes were required, and call them 1-by-1. Sorry if I've got this all twisted in my head. I'm trying to build this so it's really flexible.

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  • virtaul function

    - by hitech
    class a { virtual void foo(void) ; }; class b : public a { public: virtual void foo(void) { cout<< "class b"; } }; int main ( ) { class a *b_ptr = new b ; b_ptr-foo(); } please guide me why the b_ptr-foo() will not call the foo() function of the class b?

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  • Java reflection framework and security

    - by Jijoy
    Hi , Assume I have a singleton class in an external lib to my application. But still I can create instances of that particular class using reflection. Like this Class clas = Class.forName(Private.class.getName()); for(Constructor c : clas.getDeclaredConstructors()){ c.setAccessible(true); Private p = (Private) c.newInstance(); System.out.println(p); } How can I restrict this ? . Thanks J

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  • Behavior of virtual function in C++

    - by Summer_More_More_Tea
    Hi everyone: I have a question, here are two class below: class Base{ public: virtual void toString(); // generic implementation } class Derive : public Base{ public: ( virtual ) void toString(); // specific implementation } The question is: If I wanna subclass of class Derive perform polymophism using a pointer of type Base, is keyword virtual in the bracket necessary? If the answer is no, what's the difference between member function toString of class Derive with and without virtual?

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  • Hot to get rid of memory allocations/deallocations in swig wrappers?

    - by Dmitriy Matveev
    I want to use swig for generation of read-only wrappers for a complex object. The object which I want to wrap will always be existent while I will read it. And also I will only use my wrappers at the time that object is existent, thus I don't need any memory management from SWIG. For following swig interface: %module test %immutable; %inline %{ struct Foo { int a; }; struct Bar { int b; Foo f; }; %} I will have a wrappers which will have a lot of garbage in generated interfaces and do useless work which will reduce performance in my case. Generated java wrapper for Bar class will be like this: public class Bar { private long swigCPtr; protected boolean swigCMemOwn; protected Bar(long cPtr, boolean cMemoryOwn) { swigCMemOwn = cMemoryOwn; swigCPtr = cPtr; } protected static long getCPtr(Bar obj) { return (obj == null) ? 0 : obj.swigCPtr; } protected void finalize() { delete(); } public synchronized void delete() { if (swigCPtr != 0) { if (swigCMemOwn) { swigCMemOwn = false; testJNI.delete_Bar(swigCPtr); } swigCPtr = 0; } } public int getB() { return testJNI.Bar_b_get(swigCPtr, this); } public Foo getF() { return new Foo(testJNI.Bar_f_get(swigCPtr, this), true); } public Bar() { this(testJNI.new_Bar(), true); } } I don't need 'swigCMemOwn' field in my wrapper since it always will be false. All code related to this field will also be useless. There are also unnecessary logic in native code: SWIGEXPORT jlong JNICALL Java_some_testJNI_Bar_1f_1get(JNIEnv *jenv, jclass jcls, jlong jarg1, jobject jarg1_) { jlong jresult = 0 ; struct Bar *arg1 = (struct Bar *) 0 ; Foo result; (void)jenv; (void)jcls; (void)jarg1_; arg1 = *(struct Bar **)&jarg1; result = ((arg1)->f); { Foo * resultptr = (Foo *) malloc(sizeof(Foo)); memmove(resultptr, &result, sizeof(Foo)); *(Foo **)&jresult = resultptr; } return jresult; } I don't need these calls to malloc and memmove. I want to force swig to resolve both of these problems, but don't know how. Is it possible?

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  • Cast into new Object, Copy values by Property Name

    - by Alex
    Hello, I have the following: Class 1 (Text, State, Level) Class 2 (Text, State, Level, Ident) Is there a way for me to cast an object of Class 2 into into Class 1, and not having to do the usual cast code (Text = c.Text, State = c.State etc.)? Possibly by identifying the property names of each class and copying the value over?

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  • C#, cannot understand this error?

    - by 5YrsLaterDBA
    I am using VS2008. I have a project, SystemSoftware project, connect with a database and we are using L2E. I have a RuntimeInfo class which contains some shared information there. It looks like this: public class RuntimeInfo { public const int PWD_ExpireDays = 30; private static RuntimeInfo thisObj = new RuntimeInfo(); public static string AndeDBConnStr = ConfigurationManager.ConnectionStrings["AndeDBEntities"].ConnectionString; private RuntimeInfo() { } /// <summary> /// /// </summary> /// <returns>Return this singleton object</returns> public static RuntimeInfo getRuntimeInfo() { return thisObj; } } Now I added a helper project, AndeDataViewer, to the solution which creates a simple UI to display data from the database for testing/verification purpose. I don't want to create another set of Entity Data Model in the helper project. I just added all related files as a link in the new helper project. In the AndeDataViewer project, I get the connection string from above RuntimeInfo class which is a class from my SystemSoftware project as a linked file. The code in AndeDataViewer is like this: public class DbAccess : IDisposable { private String connStr = String.Empty; public DbAccess() { connStr = RuntimeInfo.AndeDBConnStr; } } My SystemSoftware works fine that means the RuntimeInfo class has no problem there. But when I run my AndeDataViewer, the statement inside above constructor, connStr = RuntimeInfo.AndeDBConnStr; , throws an exception. The exception is copied here: System.TypeInitializationException was unhandled Message="The type initializer for 'MyCompany.SystemSoftware.SystemInfo.RuntimeInfo' threw an exception." Source="AndeDataViewer" TypeName="MyCompany.SystemSoftware.SystemInfo.RuntimeInfo" StackTrace: at AndeDataViewer.DbAccess..ctor() in C:\workspace\SystemSoftware\Other\AndeDataViewer\AndeDataViewer\DbAccess.cs:line 17 at AndeDataViewer.Window1.rbRawData_Checked(Object sender, RoutedEventArgs e) in C:\workspace\SystemSoftware\Other\AndeDataViewer\AndeDataViewer\Window1.xaml.cs:line 69 at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs) .... InnerException: System.NullReferenceException Message="Object reference not set to an instance of an object." Source="AndeDataViewer" StackTrace: at MyCompany.SystemSoftware.SystemInfo.RuntimeInfo..cctor() in C:\workspace\SystemSoftware\SystemSoftware\src\systeminfo\RuntimeInfo.cs:line 24 InnerException: I cannot understand this because it looks fine to me but why there is an exception? we cannot access static variable when a class is a linked class? A linked class should be the same as the local class I think. "Linked" here means when I add file I use "Add As Link".

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  • Which is the better way to avoid magic string keys? Using string const keys in a class or using enumeration?

    - by user596314
    My idea is to avoid magic string keys in my Asp.Net MVC application. To do so, I want to create string constant keys to be shared in the application. For example, I can write TempData[MyClass.Message] or TempData[MyEnum.Message.ToString()] instead of TempData["Message"]. public class MyClass { public const string Message = "Message"; } and public enum MyEnum { Message, Others } My questions are: Which is the better way to avoid magic string keys? Using string const keys in a class or using enumeration together with ToString()?

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  • Confusion over C++ new operator and classes

    - by Nils
    Hi all I created a simple class in C++ which has a private dynamic array. In the constructor I initialize the array using new and in the destructor I free it using delete. When I instantiate the class using Class a = Class(..); it works as expected, however it seems I cannot instantiate it using the new operator (Like Class *a = new Class(..);), I always get a segmentation fault. What I don't understand is when I should use new to instantiate a class and when just call the constructor or should it be possible to instantiate a class either with new or by just calling the constructor. float** A = new float*[3]; for (int i=0; i<3; i++) { A[i] = new float[3]; } A[0][0] = 3; A[0][1] = 3; A[0][2] = 4; A[1][0] = 5; A[1][1] = 6; A[1][2] = 7; A[2][0] = 1; A[2][1] = 2; A[2][2] = 3; Matrix *M = new Matrix(A, 3, 3); delete[] A; delete M; Below the class definition.. class Matrix { private: int width; int height; int stride; float* elements; public: Matrix(float** a, int n, int m); ~Matrix(); }; Matrix::Matrix(float** a, int n, int m) { // n: num rows // m: elem per rows elements = new float[n*m]; for (int i=0; i<n; i++) { for (int j=0; j<m; j++) { elements[i*n + j] = a[n][m]; } } } Matrix::~Matrix() { delete[] elements; }

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  • Jquery to max number from a set of divs

    - by Matias
    Guys, Given the following HTML <div class"myclass">10</div> <div class"myclass">25</div> <div class"myclass">50</div> <div class"myclass">20</div> I want Jquery to return the maximum value found on divs with class:"myclass". (This is 50) I thought of using .find.text() will be a good starting point but cant figure out exactly how, Help is greatly appreciatted, Thanks

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  • jquery .find to get the text in a <li>

    - by Chris
    So I have a series of 2 nested ul's. When you click on the text (which is in an a tag) in the li, my page makes that editable and adds a save button. clicking the save button needs to give me back the new text inside that li and the id of that li. The id is not a problem. I'm trying to use jQuery's .find to select that anchor tag (which is successful) but i can't seem to get the text from it. Here is an example of the first list and it's sublists. <ul class='lists'> <li class='list1'> <a class='a list' id='list1'> List 1 Name</a> <img id='savelist1id' onClick="SaveName(this.parentNode.id)" src='save.jpg'> <ul class='list1subs'> <li class='sub1'> <a class='a sub' id='sub1id'> Sub 1 Name</a> <img id='savesub1id' onClick="SaveName(this.parentNode.id)" src='save.jpg'> </li> <li class='sub3'> <a class='a sub' id='sub2id'> Sub 2 Name</a> <img id='savesub2id' onClick="SaveName(this.parentNode.id)" src='save.jpg'> </li> <li class='sub2'> <a class='a sub' id='sub3id'> Sub 3 Name</a> <img id='savesub3id' onClick="SaveName(this.parentNode.id)" src='save.jpg'> </li> </ul> </li> </ul> Here's the code for identifying which save button you clicked. function SaveName(parentid){ $('li').find('a').each(function(){ if (this.id == parentid){ alert(this.id+' '+this.text) } } }); I am wanting this.text to show me the text inside the anchor tags. Help, please?

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  • Python new-style classes and __subclasses__ function

    - by Fraser Graham
    Can somebody explain to me why this works (in Python 2.5) : class Foo(object): pass class Bar(Foo): pass print(Foo.__subclasses__()) but this doesn't : class Foo(): pass class Bar(Foo): pass print(Foo.__subclasses__()) The latter returns "AttributeError: class Foo has no attribute '__subclasses__'" but i'm not sure why. I know this is related to old-style vs. new-style classes but i'm not clear on why that would make this functionality unavailable.

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