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• jQuery add class is not working

  - by user1269625

  Hey ya'll I have this code here and it suppose to add the class name "cboxElement" $(".wpcart_gallery a:first").addClass("cboxElement"); but it does not work. I have the proper Jquery file in my header, I have surrounded this in jQuery('document').ready(function($){......}); and it works for all my other Jquery but the add class call. here is what I am trying to add the class to... <div class="wpcart_gallery" style="text-align:center; padding-top:5px;"> <a class="thickbox" href="DSC_0037.jpg" rev="DSC_0037.jpg"></a> </div> Anybody know why this isnt working? I am new to jquery this is also in wordpress hence the jQuery('document')

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• abstract class MouseAdapter vs. interface

  - by Stefano Borini

  I noted this (it's a java.awt.event class). public abstract class MouseAdapter implements MouseListener, MouseWheelListener, MouseMotionListener { .... } Then you are clearly forced to extend from this adapter public class MouseAdapterImpl extends MouseAdapter {} the class is abstract and implements no methods. Is this a strategy to combine different interfaces into a single "basically interface" ? I assume in java it's not possible to combine different interfaces into a single one without using this approach. In other words, it's not possible to do something like this in java public interface MouseAdapterIface extends MouseListener, MouseWheelListener, MouseMotionListener { } and then eventually public class MouseAdapterImpl implements MouseAdapterIface {} Is my understanding of the point correct ? what about C# ?

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• abstract method signature, inheritance, and "Do" naming convention

  - by T. Webster

  I'm learning about design patterns and in examples of code I've seen a convention where the abstract class declares a method, for example: public abstract class ServiceBase { ... public virtual object GetSomething(); and then protected abstract object DoGetSomething(); My question is on why these two methods exist, since they appear to serve the same purpose. Is this so that the base class GetSomething() method logic cannot be overridden by inherited classes? But then again, the method is marked virtual, so it can be overridden anyway. What is the usefulness here in requiring derived class implementers to implement the abstract method when the virtual method can be called anyway?

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• Ruby get inheriting class

  - by Brian D.

  I'm working on creating my first plugin for rails. I'm still pretty new to ruby and I was wondering if its possible to get the inheriting class? For example, I'm trying to create a plugin that will allow unit testing and functional testing when you are not using migrations. What I'm trying to do is initialize a class variable named controller to be initialized to the type of controller that is being tested. If I have a base class ControllerTest: class ControllerTest < Test::Unit::TestCase attr_accessor :controller def initialize super @controller = "call function that will find the inheriting classes name and create an instance of that controller type." end end So what I'm currently stuck on is getting the name of the inheriting class. Is this possible? And if not, does anyone know another way on how I could go about implementing this? Thanks in advance.

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• Get Function Pointer to function in a shared library I didn't directly load

  - by bdk

  My Linux application (A) links against a Third Party shared Library (B) which I don't have source code to. This library makes use of another third party shared library that I don't have source code to (C). I believe that (B) uses dlopen to access (C) instead of directly linking. My reasoning for this is that 'ldd' on (B) does not show (C) and objdump -X (B) shows references to dlopen/dlclose/dlsym. My requirement is that I need to in my code for (A) get a function pointer to a function foo() located in (C). Normally I'd use dlsym for this, but I need to pass it the handle returned from dlopen which I don't have since (B) does not expose this. - For the larger context: I need to modify the function in (C) such that everytime it calls its helper function bar() (also located in (C)), it also calls a function with the same signature located in (A) with the same parameters (Basically inject my code into the codepath of (C) foo()-bar(). I believe I've found a way to accomplish this using gdb, but in order to port my gdb command list, but I'm stuck on the step of getting the function pointer. I'm also open to alternatives to accomplish the same task rather than the exact problem as stated above Edit: After writing this I realized I can probably just do another dlopen on the file in my code and the symbols returned via dlsym on that handle should be the same as received via the original dlopen, If I'm reading the dlopen man page correctly. However I'm still interested in advice or assistance with the my larger context, If theres a better way to go about this

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• accessing base class's method with derived class's object which has a method of same name.

  - by ashish yadav

  when accessing foo() of "base" using derived class's object. include class base { public: void foo() { std::cout<<"\nHello from foo\n"; } }; class derived : public base { public: void foo(int k) { std::cout<<"\nHello from foo with value = "< } how to access base class method having a method of same name in derived class. the error generated has been shown. i apologize if i am not clear but i feel i have made myself clear as water. thanks in advance.

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• iTunes 9 not sorting albums by track order consistently

  - by joshhunt

  I have my iTunes library set to sort by music by Artist, then album (). For most of my albums this will also sort the albums in the correct track listing order (using the track number tag). Except for one album: As you can see, "The Boy Who Knew Too Much" seems to sort erratically. Why is this happening and how can I fix it?

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• C#: Abstract classes need to implement interfaces?

  - by bguiz

  My test code in C#: namespace DSnA { public abstract class Test : IComparable { } } Results in the following compiler error: error CS0535: 'DSnA.Test' does not implement interface member 'System.IComparable.CompareTo(object)' Since the class Test is an abstract class, why does the compiler require it to implement the interface? Shouldn't this requirement only be compulsory for concrete classes?

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• Class Not found exception in JApplet.

  - by Nitesh Panchal

  Hello, I created a simple Applet using JApplet and everything seems to work fine but as soon i create an object of my userdefined class named ChatUser in my applet, i get this error :- SEVERE: java.lang.ClassNotFoundException: applet.ChatUser at com.sun.enterprise.loader.ASURLClassLoader.findClassData(ASURLClassLoader.java:713) at com.sun.enterprise.loader.ASURLClassLoader.findClass(ASURLClassLoader.java:626) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at java.lang.ClassLoader.loadClass(ClassLoader.java:252) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:247) at java.io.ObjectInputStream.resolveClass(ObjectInputStream.java:604) at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1575) at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1496) at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1732) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1329) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at misc.ChatClient.run(ChatClient.java:43) Any idea what can be wrong? It only happens when i create an object of any user defined class. Do i need to set some security settings or something? Please help :(

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• How can I process a form's events in another class / module automatically in VB.NET

  - by CowKingDeluxe

  Here's my code: Public Class Form1 End Class Public Class Form1Handler Inherits Form1 Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click MsgBox("I") End Sub End Class I'm trying to get Form1Handler to process Form1's events automatically. How can I do this? Should I use a module instead? I'm doing this in VB 2010. I don't want to have to make an event handler in Form1 and then pipe it to the other class / module, is there some way to automatically "pipe" the events from form1 to form1handler?

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• Properly design a code editor application

  - by Hemaulo

  I'm working on personal project which is basically a code editor. Imagine standard File menu with menu items New, Open, Save, Save As, Save All, Close, Close All. I'm stuck with proper design. Currently I have: A Document class which represents a document - code editing control, respective tab in tab bar and various properties such as Caption, Filename, IsModified etc. A Documents class which represents all open documents. Contains methods like New, Open(FileName), ... The problem is that I can't figure out which class / menu command is responsible for which tasks. For example, with File-New menu command is simple - call Documents.New and that's it. But what for File-Open? The Documents.Open method expects filename as a parameter. So before calling this method I need to open an file selection dialog, let user select files and for each file call Documents.Open(FileName). Where is best place for this supporting code, in menu command, rewrite Documents.Open and put it there? The same with Save actions. Which is responsible for saving? Is it Documents class which uses Document.Editor.SaveToFile(FileName) or better create Save method in Document class? Somewhere in the middle also need to ask user if he wants to save current document... I'm stuck. Any ideas? Edited: The programming language is Delphi.

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• Xlib.h and Xutil.h not found in Eclipse, how can I fix this?

  - by eclipseNoob

  Hi, I'm a newbie to Eclipse IDE for C/C++ development. I just installed MingW and set it up as my system's environment variable. I am trying to make an application that uses the X library but eclipse cant seem to find it. Eclipse works with any other simple standard library functions but it cant find the X library. Please Help! Here's a sample code snippet that's failing: #include <stdio.h> #include <X11/Xlib.h> // Can't find this #include <X11/Xutil.h> // Or this... int main() { printf("Hello"); return 0; } Do I have to download the X library from somewhere? If so then from where and where do I paste it to? Please tell me what to do in order for me to start coding using the Xlib in Eclipse. If you find any useful links, please dont hesitate to post. Thanks.

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• Ruby: Calling class method from instance

  - by Peter

  In Ruby, how do you call a class method from one of that class's instances? Say I have class Truck def self.default_make # Class method. "mac" end def initialize # Instance method. Truck.default_make # gets the default via the class's method. # But: I wish to avoid mentioning Truck. Seems I'm repeating myself. end end the line Truck.default_make retrieves the default. But is there a way of saying this without mentioning Truck? It seems like there should be.

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• In PHP, is it possible to create an instance of an class without calling class's constructor ?

  - by Rachel

  By any means, is it possible to create an instance of an php class without calling its constructor ? I have Class A and while creating an instance of it am passing file and in constructor of Class A am opening the file. Now in Class A, there is function which I need to call but am not required to pass file and so there is not need to use constructor functionality of opening file as am not passing file. So my question is, Is it possible by any means to create an instance of an PHP class without calling its constructor ?

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• Using static mutex in a class

  - by Dmitry Yudakov

  I have a class that I can have many instances of. Inside it creates and initializes some members from a 3rd party library (that use some global variables) and is not thread-safe. I thought about using static boost::mutex, that would be locked in my class constructor and destructor. Thus creating and destroying instances among my threads would be safe for the 3rd party members. class MyClass { static boost::mutex mx; // 3rd party library members public: MyClass(); ~MyClass(); }; MyClass::MyClass() { boost::mutex::scoped_lock scoped_lock(mx); // create and init 3rd party library stuff } MyClass::~MyClass() { boost::mutex::scoped_lock scoped_lock(mx); // destroy 3rd party library stuff } I cannot link because I receive error: undefined reference to `MyClass::mx` Do I need some special initialization of such static member? Is the whole conception of static mutex wrong?

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• Wicket app in embedded Jetty causes UnsupportedClassVersionError

  - by Ondra Žižka

  I've tried to run a Wicket app in an embedded Jetty, using this code: public static void main( String[] args ){ Server server = new Server(8080); Context root = new Context( server, "/", Context.SESSIONS ); FilterHolder filterHolder = new FilterHolder( new WicketFilter() ); filterHolder.getInitParameters().put("applicationClassName", cz.dw.test.WicketApplication.class.getName() ); root.addFilter( filterHolder, "/*" , Handler.ALL ); try { server.start(); } catch (Exception ex) { ex.printStackTrace(); } } But I got java.lang.UnsupportedClassVersionError: Bad version number in .class file. Switching the target class version for my app (1.6 - 1.5) did not help. I use Sun JDK 1.6.0_17, Wicket 1.4.8, Jetty 6.1.24. I tried to debug, but the JRE classes have no debug data. The stacktrace is of no use as it happens when loading the classes into JVM. Any ideas what could be wrong? How can I find which class is causing this? Thanks, Ondra

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• PHP: friend classes and ungreedy caller function/class

  - by avetis.kazarian

  Is there any way to get the caller function with something else than debug_backtrace()? I'm looking for a less greedy way to simulate scopes like friend or internal. Let's say I have a class A and a class B. Until now, I've been using debug_backtrace(), which is too greedy (IMHO). I thought of something like this: <?php class A { public function __construct(B $callerObj) {} } class B { public function someMethod() { $obj = new A($this); } } ?> It might be OK if you want to limit it to one specific class, but let's say I have 300 classes, and I want to limit it to 25 of them? One way could be using an interface to aggregate: public function __construct(CallerInterface $callerObj) But it's still an ugly code. Moreover, you can't use that trick with static classes. Have any better idea?

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• Get class of caller's method (via inspect) in Python (alt: super() emulator)

  - by Slava Vishnyakov

  Is it possible to get reference to class B in this example? class A(object): pass class B(A): def test(self): test2() class C(B): pass import inspect def test2(): frame = inspect.currentframe().f_back cls = frame.[?something here?] # cls here should == B (class) c = C() c.test() Basically, C is child of B, B is child of A. Then we create c of type C. Then the call to c.test() actually calls B.test() (via inheritance), which calls to test2(). test2() can get the parent frame frame; code reference to method via frame.f_code; self via frame.f_locals['self']; but type(frame.f_locals['self']) is C (of course), but not B, where method is defined. Any way to get B?

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• Ruby: Locate class definition at run time?

  - by Thor Thurn

  I'm having an odd probably with rails right now... a class is being defined somewhere, and I can't find it. Grepping for "class ClassName" hasn't managed to locate it, but it's definitely there when I load up the rails console. It's just a vanilla class inheriting from Object with nothing else defined... quite boring. So, what I'd like is a way to figure out where this class constant was originally defined from the rails console. Something to print out the value of '__ FILE __' when this class was declared, in other words. I feel like some type of metaprogramming should make this possible.

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• spring-nullpointerexception- cant access autowired annotated service (or dao) in a no-annotations class

  - by user286806

  I have this problem that I cannot fix. From my @Controller, i can easily access my autowired @Service class and play with it no problem. But when I do that from a separate class without annotations, it gives me a NullPointerException. My Controller (works)- @Controller public class UserController { @Autowired UserService userService;... My separate Java class (not working)- public final class UsersManagementUtil { @Autowired UserService userService; or @Autowired UserDao userDao; userService or userDao are always null! Was just trying if any one of them works. My component scan setting has the root level package set for scanning so that should be OK. my servlet context - <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd"> <!-- the application context definition for the springapp DispatcherServlet --> <!-- Enable annotation driven controllers, validation etc... --> <context:property-placeholder location="classpath:jdbc.properties" /> <context:component-scan base-package="x" /> <tx:annotation-driven transaction-manager="hibernateTransactionManager" /> <!-- package shortended --> <bean id="messageSource" class="o.s.c.s.ReloadableResourceBundleMessageSource"> <property name="basename" value="/WEB-INF/messages" /> </bean> <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource"> <property name="driverClassName" value="${database.driver}" /> <property name="url" value="${database.url}" /> <property name="username" value="${database.user}" /> <property name="password" value="${database.password}" /> </bean> <!-- package shortened --> <bean id="viewResolver" class="o.s.w.s.v.InternalResourceViewResolver"> <property name="prefix"> <value>/</value> </property> <property name="suffix"> <value>.jsp</value> </property> <property name="order"> <value>0</value> </property> </bean> <!-- package shortened --> <bean id="sessionFactory" class="o.s.o.h3.a.AnnotationSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="annotatedClasses"> <list> <value>orion.core.models.Question</value> <value>orion.core.models.User</value> <value>orion.core.models.Space</value> <value>orion.core.models.UserSkill</value> <value>orion.core.models.Question</value> <value>orion.core.models.Rating</value> </list> </property> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect">${hibernate.dialect}</prop> <prop key="hibernate.show_sql">${hibernate.show_sql}</prop> <prop key="hibernate.hbm2ddl.auto">${hibernate.hbm2ddl.auto}</prop> </props> </property> </bean> <bean id="hibernateTransactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager"> <property name="sessionFactory" ref="sessionFactory" /> </bean> Any clue?

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• How to programatically read native DLL imports in C#?

  - by Eric

  The large hunk of C# code below is intended to print the imports of a native DLL. I copied it from from this link and modified it very slightly, just to use LoadLibraryEx as Mike Woodring does here. I find that when I call the Foo.Test method with the original example's target, MSCOREE.DLL, it prints all the imports fine. But when I use other dlls like GDI32.DLL or WSOCK32.DLL the imports do not get printed. What's missing from this code that would let it print all the imports as, for example, DUMPBIN.EXE does? (Is there a hint I'm not grokking in the original comment that says, "using mscoree.dll as an example as it doesnt export any thing"?) Here's the extract that just shows how it's being invoked: public static void Test() { // WORKS: var path = @"c:\windows\system32\mscoree.dll"; // NO ERRORS, BUT NO IMPORTS PRINTED EITHER: //var path = @"c:\windows\system32\gdi32.dll"; //var path = @"c:\windows\system32\wsock32.dll"; var hLib = LoadLibraryEx(path, 0, DONT_RESOLVE_DLL_REFERENCES | LOAD_IGNORE_CODE_AUTHZ_LEVEL); TestImports(hLib, true); } And here is the whole code example: namespace PETest2 { [StructLayout(LayoutKind.Explicit)] public unsafe struct IMAGE_IMPORT_BY_NAME { [FieldOffset(0)] public ushort Hint; [FieldOffset(2)] public fixed char Name[1]; } [StructLayout(LayoutKind.Explicit)] public struct IMAGE_IMPORT_DESCRIPTOR { #region union /// <summary> /// CSharp doesnt really support unions, but they can be emulated by a field offset 0 /// </summary> [FieldOffset(0)] public uint Characteristics; // 0 for terminating null import descriptor [FieldOffset(0)] public uint OriginalFirstThunk; // RVA to original unbound IAT (PIMAGE_THUNK_DATA) #endregion [FieldOffset(4)] public uint TimeDateStamp; [FieldOffset(8)] public uint ForwarderChain; [FieldOffset(12)] public uint Name; [FieldOffset(16)] public uint FirstThunk; } [StructLayout(LayoutKind.Explicit)] public struct THUNK_DATA { [FieldOffset(0)] public uint ForwarderString; // PBYTE [FieldOffset(4)] public uint Function; // PDWORD [FieldOffset(8)] public uint Ordinal; [FieldOffset(12)] public uint AddressOfData; // PIMAGE_IMPORT_BY_NAME } public unsafe class Interop { #region Public Constants public static readonly ushort IMAGE_DIRECTORY_ENTRY_IMPORT = 1; #endregion #region Private Constants #region CallingConvention CALLING_CONVENTION /// <summary> /// Specifies the calling convention. /// </summary> /// <remarks> /// Specifies <see cref="CallingConvention.Winapi" /> for Windows to /// indicate that the default should be used. /// </remarks> private const CallingConvention CALLING_CONVENTION = CallingConvention.Winapi; #endregion CallingConvention CALLING_CONVENTION #region IMPORT DLL FUNCTIONS private const string KERNEL_DLL = "kernel32"; private const string DBGHELP_DLL = "Dbghelp"; #endregion #endregion Private Constants [DllImport(KERNEL_DLL, CallingConvention = CALLING_CONVENTION, EntryPoint = "GetModuleHandleA"), SuppressUnmanagedCodeSecurity] public static extern void* GetModuleHandleA(/*IN*/ char* lpModuleName); [DllImport(KERNEL_DLL, CallingConvention = CALLING_CONVENTION, EntryPoint = "GetModuleHandleW"), SuppressUnmanagedCodeSecurity] public static extern void* GetModuleHandleW(/*IN*/ char* lpModuleName); [DllImport(KERNEL_DLL, CallingConvention = CALLING_CONVENTION, EntryPoint = "IsBadReadPtr"), SuppressUnmanagedCodeSecurity] public static extern bool IsBadReadPtr(void* lpBase, uint ucb); [DllImport(DBGHELP_DLL, CallingConvention = CALLING_CONVENTION, EntryPoint = "ImageDirectoryEntryToData"), SuppressUnmanagedCodeSecurity] public static extern void* ImageDirectoryEntryToData(void* Base, bool MappedAsImage, ushort DirectoryEntry, out uint Size); } static class Foo { // From winbase.h in the Win32 platform SDK. // const uint DONT_RESOLVE_DLL_REFERENCES = 0x00000001; const uint LOAD_IGNORE_CODE_AUTHZ_LEVEL = 0x00000010; [DllImport("kernel32.dll"), SuppressUnmanagedCodeSecurity] static extern uint LoadLibraryEx(string fileName, uint notUsedMustBeZero, uint flags); public static void Test() { //var path = @"c:\windows\system32\mscoree.dll"; //var path = @"c:\windows\system32\gdi32.dll"; var path = @"c:\windows\system32\wsock32.dll"; var hLib = LoadLibraryEx(path, 0, DONT_RESOLVE_DLL_REFERENCES | LOAD_IGNORE_CODE_AUTHZ_LEVEL); TestImports(hLib, true); } // using mscoree.dll as an example as it doesnt export any thing // so nothing shows up if you use your own module. // and the only none delayload in mscoree.dll is the Kernel32.dll private static void TestImports( uint hLib, bool mappedAsImage ) { unsafe { //fixed (char* pszModule = "mscoree.dll") { //void* hMod = Interop.GetModuleHandleW(pszModule); void* hMod = (void*)hLib; uint size = 0; uint BaseAddress = (uint)hMod; if (hMod != null) { Console.WriteLine("Got handle"); IMAGE_IMPORT_DESCRIPTOR* pIID = (IMAGE_IMPORT_DESCRIPTOR*)Interop.ImageDirectoryEntryToData((void*)hMod, mappedAsImage, Interop.IMAGE_DIRECTORY_ENTRY_IMPORT, out size); if (pIID != null) { Console.WriteLine("Got Image Import Descriptor"); while (!Interop.IsBadReadPtr((void*)pIID->OriginalFirstThunk, (uint)size)) { try { char* szName = (char*)(BaseAddress + pIID->Name); string name = Marshal.PtrToStringAnsi((IntPtr)szName); Console.WriteLine("pIID->Name = {0} BaseAddress - {1}", name, (uint)BaseAddress); THUNK_DATA* pThunkOrg = (THUNK_DATA*)(BaseAddress + pIID->OriginalFirstThunk); while (!Interop.IsBadReadPtr((void*)pThunkOrg->AddressOfData, 4U)) { char* szImportName; uint Ord; if ((pThunkOrg->Ordinal & 0x80000000) > 0) { Ord = pThunkOrg->Ordinal & 0xffff; Console.WriteLine("imports ({0}).Ordinal{1} - Address: {2}", name, Ord, pThunkOrg->Function); } else { IMAGE_IMPORT_BY_NAME* pIBN = (IMAGE_IMPORT_BY_NAME*)(BaseAddress + pThunkOrg->AddressOfData); if (!Interop.IsBadReadPtr((void*)pIBN, (uint)sizeof(IMAGE_IMPORT_BY_NAME))) { Ord = pIBN->Hint; szImportName = (char*)pIBN->Name; string sImportName = Marshal.PtrToStringAnsi((IntPtr)szImportName); // yes i know i am a lazy ass Console.WriteLine("imports ({0}).{1}@{2} - Address: {3}", name, sImportName, Ord, pThunkOrg->Function); } else { Console.WriteLine("Bad ReadPtr Detected or EOF on Imports"); break; } } pThunkOrg++; } } catch (AccessViolationException e) { Console.WriteLine("An Access violation occured\n" + "this seems to suggest the end of the imports section\n"); Console.WriteLine(e); } pIID++; } } } } } Console.WriteLine("Press Any Key To Continue......"); Console.ReadKey(); } }

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• Trying to understand the usage of class_eval

  - by eMxyzptlk

  Hello everyone, I'm using the rails-settings gem, and I'm trying to understand how you add functions to ActiveRecord classes (I'm building my own library for card games), and I noticed that this gem uses one of the Meta-programming techniques to add the function to the ActiveRecord::Base class (I'm far from Meta-programming master in ruby, but I'm trying to learn it) module RailsSettings class Railtie < Rails::Railtie initializer 'rails_settings.initialize', :after => :after_initialize do Railtie.extend_active_record end end class Railtie def self.extend_active_record ActiveRecord::Base.class_eval do def self.has_settings class_eval do def settings RailsSettings::ScopedSettings.for_thing(self) end scope :with_settings, :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :select => "DISTINCT #{self.table_name}.*" scope :with_settings_for, lambda { |var| { :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'" } } scope :without_settings, :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :conditions => 'settings.id IS NULL' scope :without_settings_for, lambda { |var| { :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'", :conditions => 'settings.id IS NULL' } } end end end end end end What I don't understand is why he uses class_eval on ActiveRecord::Base, wasn't it easier if he just open the ActiveRecord::Base class and define the functions? Specially that there's nothing dynamic in the block (What I mean by dynamic is when you do class_eval or instance_eval on a string containing variables) something like this: module ActiveRecord class Base def self.has_settings class_eval do def settings RailsSettings::ScopedSettings.for_thing(self) end scope :with_settings, :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :select => "DISTINCT #{self.table_name}.*" scope :with_settings_for, lambda { |var| { :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'" } } scope :without_settings, :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :conditions => 'settings.id IS NULL' scope :without_settings_for, lambda { |var| { :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'", :conditions => 'settings.id IS NULL' } } end end end end I understand the second class_eval (before the def settings) is to define functions on the fly on every class that 'has_settings' right ? Same question here, I think he could use "def self.settings" instead of "class_eval.... def settings", no ?

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• C++: select argmax over vector of classes w.r.t. arbitrary expression

  - by karpathy

  Hello, I have trouble describing my problem so I'll give an example: I have a class description that has a couple of variables in it, for example: class A{ float a, b, c, d; } Now, I maintain a vector<A> that contains many of these classes. What I need to do very very often is to find the object inside this vector that satisfies that one of it's parameters is maximal w.r.t to the others. i.e code looks something like: int maxi=-1; float maxa=-1000; for(int i=0;i<vec.size();i++){ res= vec[i].a; if(res > maxa) { maxa= res; maxi=i; } } return vec[maxi]; However, sometimes I need to find class with maximal a, sometimes with maximal b, sometimes the class with maximal 0.8*a + 0.2*b, sometimes I want a maximal a*VAR + b, where VAR is some variable that is assigned in front, etc. In other words, I need to evaluate an expression for every class, and take the max. I find myself copy-pasting this everywhere, and only changing the single line that defines res. What makes it even more complicated is that even the name of the vector changes. Sometimes it's vec, sometimes it can be something else. I have many vectors that contain A's. This could be changed if this makes the problem too hard. Is there some nice way to avoid this insanity in C++? What's the neatest way to handle this? Thank you!

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• Hide struct definition in static library.

  - by BobMcLaury

  Hi, I need to provide a C static library to the client and need to be able to make a struct definition unavailable. On top of that I need to be able to execute code before the main at library initialization using a global variable. Here's my code: private.h #ifndef PRIVATE_H #define PRIVATE_H typedef struct TEST test; #endif private.c (this should end up in a static library) #include "private.h" #include <stdio.h> struct TEST { TEST() { printf("Execute before main and have to be unavailable to the user.\n"); } int a; // Can be modified by the user int b; // Can be modified by the user int c; // Can be modified by the user } TEST; main.c test t; int main( void ) { t.a = 0; t.b = 0; t.c = 0; return 0; } Obviously this code doesn't work... but show what I need to do... Anybody knows how to make this work? I google quite a bit but can't find an answer, any help would be greatly appreciated. TIA!

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• JBoss classloading when 2 WARs have the same class

  - by Pacman

  I have a web applications A.war which has two servlets AServlet and BServlet. Both instantiate a helper class com.mycompany.Foo.class (this is my own class, not a third party library). Now I want to split the two servlets into two separate WARs: A.war will have only AServlet and a new B.war will have BServlet. AServlet will invoke BServlet via HTTP GET. Both WARs will have com.mycompany.Foo.class. I want to deploy both WARs on the same JBoss instance. The question is, will there be any classloading issues due to the same class being present in both WARs, and the WARs being deployed on the same JBoss instance?

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