Search Results

Search found 20786 results on 832 pages for 'static variables'.

Page 182/832 | < Previous Page | 178 179 180 181 182 183 184 185 186 187 188 189  | Next Page >

  • C# Delegate under the hood question.

    - by Ted
    Hi Guys I was doing some digging around into delegate variance after reading the following tquestion in SO. "delegate-createdelegate-and-generics-error-binding-to-target-method" (sorry not allowed to post more than one hyperlink as a newbie here!) I found a very nice bit of code from Barry kelly at https://www.blogger.com/comment.g?blogID=8184237816669520763&postID=2109708553230166434 Here it is (in a sugared-up form :-) using System; namespace ConsoleApplication4 { internal class Base { } internal class Derived : Base { } internal delegate void baseClassDelegate(Base b); internal delegate void derivedClassDelegate(Derived d); internal class App { private static void Foo1(Base b) { Console.WriteLine("Foo 1"); } private static void Foo2(Derived b) { Console.WriteLine("Foo 2"); } private static T CastDelegate<T>(Delegate src) where T : class { return (T) (object) Delegate.CreateDelegate( typeof (T), src.Target, src.Method, true); // throw on fail } private static void Main() { baseClassDelegate a = Foo1; // works fine derivedClassDelegate b = Foo2; // works fine b = a.Invoke; // the easy way to assign delegate using variance, adds layer of indirection though b(new Derived()); b = CastDelegate<derivedClassDelegate>(a); // the hard way, avoids indirection b(new Derived()); } } } I understand all of it except this one (what looks very simple) line. b = a.Invoke; // the easy way to assign delegate using variance, adds layer of indirection though Can anyone tell me: how it is possible to call invoke without passing the param required by the static function. When is going on under the hood when you assign the return value from calling invoke What does Barry mean by extra indirection (in his comment)

    Read the article

  • Traditional IO vs memory-mapped

    - by Senne
    I'm trying to illustrate the difference in performance between traditional IO and memory mapped files in java to students. I found an example somewhere on internet but not everything is clear to me, I don't even think all steps are nececery. I read a lot about it here and there but I'm not convinced about a correct implementation of neither of them. The code I try to understand is: public class FileCopy{ public static void main(String args[]){ if (args.length < 1){ System.out.println(" Wrong usage!"); System.out.println(" Correct usage is : java FileCopy <large file with full path>"); System.exit(0); } String inFileName = args[0]; File inFile = new File(inFileName); if (inFile.exists() != true){ System.out.println(inFileName + " does not exist!"); System.exit(0); } try{ new FileCopy().memoryMappedCopy(inFileName, inFileName+".new" ); new FileCopy().customBufferedCopy(inFileName, inFileName+".new1"); }catch(FileNotFoundException fne){ fne.printStackTrace(); }catch(IOException ioe){ ioe.printStackTrace(); }catch (Exception e){ e.printStackTrace(); } } public void memoryMappedCopy(String fromFile, String toFile ) throws Exception{ long timeIn = new Date().getTime(); // read input file RandomAccessFile rafIn = new RandomAccessFile(fromFile, "rw"); FileChannel fcIn = rafIn.getChannel(); ByteBuffer byteBuffIn = fcIn.map(FileChannel.MapMode.READ_WRITE, 0,(int) fcIn.size()); fcIn.read(byteBuffIn); byteBuffIn.flip(); RandomAccessFile rafOut = new RandomAccessFile(toFile, "rw"); FileChannel fcOut = rafOut.getChannel(); ByteBuffer writeMap = fcOut.map(FileChannel.MapMode.READ_WRITE,0,(int) fcIn.size()); writeMap.put(byteBuffIn); long timeOut = new Date().getTime(); System.out.println("Memory mapped copy Time for a file of size :" + (int) fcIn.size() +" is "+(timeOut-timeIn)); fcOut.close(); fcIn.close(); } static final int CHUNK_SIZE = 100000; static final char[] inChars = new char[CHUNK_SIZE]; public static void customBufferedCopy(String fromFile, String toFile) throws IOException{ long timeIn = new Date().getTime(); Reader in = new FileReader(fromFile); Writer out = new FileWriter(toFile); while (true) { synchronized (inChars) { int amountRead = in.read(inChars); if (amountRead == -1) { break; } out.write(inChars, 0, amountRead); } } long timeOut = new Date().getTime(); System.out.println("Custom buffered copy Time for a file of size :" + (int) new File(fromFile).length() +" is "+(timeOut-timeIn)); in.close(); out.close(); } } When exactly is it nececary to use RandomAccessFile? Here it is used to read and write in the memoryMappedCopy, is it actually nececary just to copy a file at all? Or is it a part of memorry mapping? In customBufferedCopy, why is synchronized used here? I also found a different example that -should- test the performance between the 2: public class MappedIO { private static int numOfInts = 4000000; private static int numOfUbuffInts = 200000; private abstract static class Tester { private String name; public Tester(String name) { this.name = name; } public long runTest() { System.out.print(name + ": "); try { long startTime = System.currentTimeMillis(); test(); long endTime = System.currentTimeMillis(); return (endTime - startTime); } catch (IOException e) { throw new RuntimeException(e); } } public abstract void test() throws IOException; } private static Tester[] tests = { new Tester("Stream Write") { public void test() throws IOException { DataOutputStream dos = new DataOutputStream( new BufferedOutputStream( new FileOutputStream(new File("temp.tmp")))); for(int i = 0; i < numOfInts; i++) dos.writeInt(i); dos.close(); } }, new Tester("Mapped Write") { public void test() throws IOException { FileChannel fc = new RandomAccessFile("temp.tmp", "rw") .getChannel(); IntBuffer ib = fc.map( FileChannel.MapMode.READ_WRITE, 0, fc.size()) .asIntBuffer(); for(int i = 0; i < numOfInts; i++) ib.put(i); fc.close(); } }, new Tester("Stream Read") { public void test() throws IOException { DataInputStream dis = new DataInputStream( new BufferedInputStream( new FileInputStream("temp.tmp"))); for(int i = 0; i < numOfInts; i++) dis.readInt(); dis.close(); } }, new Tester("Mapped Read") { public void test() throws IOException { FileChannel fc = new FileInputStream( new File("temp.tmp")).getChannel(); IntBuffer ib = fc.map( FileChannel.MapMode.READ_ONLY, 0, fc.size()) .asIntBuffer(); while(ib.hasRemaining()) ib.get(); fc.close(); } }, new Tester("Stream Read/Write") { public void test() throws IOException { RandomAccessFile raf = new RandomAccessFile( new File("temp.tmp"), "rw"); raf.writeInt(1); for(int i = 0; i < numOfUbuffInts; i++) { raf.seek(raf.length() - 4); raf.writeInt(raf.readInt()); } raf.close(); } }, new Tester("Mapped Read/Write") { public void test() throws IOException { FileChannel fc = new RandomAccessFile( new File("temp.tmp"), "rw").getChannel(); IntBuffer ib = fc.map( FileChannel.MapMode.READ_WRITE, 0, fc.size()) .asIntBuffer(); ib.put(0); for(int i = 1; i < numOfUbuffInts; i++) ib.put(ib.get(i - 1)); fc.close(); } } }; public static void main(String[] args) { for(int i = 0; i < tests.length; i++) System.out.println(tests[i].runTest()); } } I more or less see whats going on, my output looks like this: Stream Write: 653 Mapped Write: 51 Stream Read: 651 Mapped Read: 40 Stream Read/Write: 14481 Mapped Read/Write: 6 What is makeing the Stream Read/Write so unbelievably long? And as a read/write test, to me it looks a bit pointless to read the same integer over and over (if I understand well what's going on in the Stream Read/Write) Wouldn't it be better to read int's from the previously written file and just read and write ints on the same place? Is there a better way to illustrate it? I've been breaking my head about a lot of these things for a while and I just can't get the whole picture..

    Read the article

  • C#.Net Calling a C++ DLL

    - by hayer
    Hi I got a DLL(without the sourcecode) which exports like this: ?ReceiveCoreDataPtr@@YAXPAX@Z ?xenoAddRigidBodyAngularImpulse@@YAXHMMM@Z ?xenoAddRigidBodyForce@@YAXHMMM@Z ?xenoAddRigidBodyForce@@YAXHMMMMMM@Z ?xenoAddRigidBodyLinearImpulse@@YAXHMMM@Z ?xenoAddRigidBodyPointImpulse@@YAXHMMMMMM@Z ?xenoAddRigidBodyTorque@@YAXHMMM@Z ?xenoCharacterControllerCrouch@@YAXH@Z ?xenoCharacterControllerJump@@YAXH@Z ?xenoCharacterDisable@@YAXH@Z ?xenoCharacterEnable@@YAXH@Z ?xenoDeleteRigidBody@@YAXH@Z ?xenoEnd@@YAXXZ ?xenoGetCameraFOV@@YAKH@Z ?xenoGetCameraPointX@@YAKH@Z ?xenoGetCameraPointY@@YAKH@Z ?xenoGetCameraPointZ@@YAKH@Z ?xenoGetCameraPositionX@@YAKH@Z ?xenoGetCameraPositionY@@YAKH@Z ?xenoGetCameraPositionZ@@YAKH@Z ?xenoGetCharacterControllerHeadPosition@@YAKH@Z ?xenoGetCharacterControllerPositionX@@YAKH@Z ?xenoGetCharacterControllerPositionY@@YAKH@Z ?xenoGetCharacterControllerPositionZ@@YAKH@Z ?xenoGetCharacterControllerRotation@@YAKH@Z ?xenoGetRigidBodyAllowedPenetrationDepth@@YAKH@Z ?xenoGetRigidBodyAngularDamping@@YAKH@Z ?xenoGetRigidBodyAngularVelocityX@@YAKH@Z ?xenoGetRigidBodyAngularVelocityY@@YAKH@Z ?xenoGetRigidBodyAngularVelocityZ@@YAKH@Z ?xenoGetRigidBodyFriction@@YAKH@Z ?xenoGetRigidBodyGravityFactor@@YAKH@Z ?xenoGetRigidBodyLinearDamping@@YAKH@Z ?xenoGetRigidBodyLinearVelocityX@@YAKH@Z ?xenoGetRigidBodyLinearVelocityY@@YAKH@Z ?xenoGetRigidBodyLinearVelocityZ@@YAKH@Z ?xenoGetRigidBodyMass@@YAKH@Z ?xenoGetRigidBodyMaxAngularVelocity@@YAKH@Z ?xenoGetRigidBodyMaxLinearVelocity@@YAKH@Z ?xenoGetRigidBodyPointVelocityX@@YAKHMMM@Z ?xenoGetRigidBodyPointVelocityY@@YAKHMMM@Z ?xenoGetRigidBodyPointVelocityZ@@YAKHMMM@Z ?xenoGetRigidBodyRestitution@@YAKH@Z ?xenoIsRigidBodyALadder@@YAHH@Z ?xenoMakeCamera@@YAXHH@Z ?xenoMakeCharacterController@@YAXHMM@Z ?xenoMakeCharacterController@@YAXHMMM@Z ?xenoMakeCharacterController@@YAXHMMMM@Z ?xenoMakeCharacterController@@YAXHMMMMM@Z ?xenoMakeCharacterController@@YAXHMMMMMM@Z ?xenoMakeCharacterController@@YAXHMMMMMMM@Z ?xenoMakeRigidBodyDynamicBox@@YAXH@Z ?xenoMakeRigidBodyDynamicBox@@YAXHM@Z ?xenoMakeRigidBodyDynamicCapsule@@YAXH@Z ?xenoMakeRigidBodyDynamicCapsule@@YAXHM@Z ?xenoMakeRigidBodyDynamicCylinder@@YAXH@Z ?xenoMakeRigidBodyDynamicCylinder@@YAXHM@Z ?xenoMakeRigidBodyDynamicSphere@@YAXH@Z ?xenoMakeRigidBodyDynamicSphere@@YAXHM@Z ?xenoMakeRigidBodyStaticBox@@YAXH@Z ?xenoMakeRigidBodyStaticCapsule@@YAXH@Z ?xenoMakeRigidBodyStaticCylinder@@YAXH@Z ?xenoMakeRigidBodyStaticSphere@@YAXH@Z ?xenoMakeRigidBodyStaticTriangleMesh@@YAXH@Z ?xenoMakeVehicle@@YAXHH@Z ?xenoMoveCharacterControllerBackward@@YAXH@Z ?xenoMoveCharacterControllerForward@@YAXH@Z ?xenoMoveCharacterControllerLeft@@YAXH@Z ?xenoMoveCharacterControllerRight@@YAXH@Z ?xenoSetCharacterControllerPosition@@YAXHMMM@Z ?xenoSetCharacterControllerRotation@@YAXHM@Z ?xenoSetGravity@@YAXM@Z ?xenoSetGravity@@YAXMMM@Z ?xenoSetRigidBodyAllowedPenetrationDepth@@YAXHM@Z ?xenoSetRigidBodyAngularDamping@@YAXHM@Z ?xenoSetRigidBodyAngularVelocity@@YAXHMMM@Z ?xenoSetRigidBodyAsLadder@@YAXHH@Z ?xenoSetRigidBodyFriction@@YAXHM@Z ?xenoSetRigidBodyGravityFactor@@YAXHM@Z ?xenoSetRigidBodyLinearDamping@@YAXHM@Z ?xenoSetRigidBodyLinearVelocity@@YAXHMMM@Z ?xenoSetRigidBodyMass@@YAXHM@Z ?xenoSetRigidBodyMaxAngularVelocity@@YAXHM@Z ?xenoSetRigidBodyMaxLinearVelocity@@YAXHM@Z ?xenoSetRigidBodyPosition@@YAXHMMM@Z ?xenoSetRigidBodyRestitution@@YAXHM@Z ?xenoSetRigidBodyRotation@@YAXHMMM@Z ?xenoSetTimeStep@@YAXM@Z ?xenoStart@@YAXH@Z ?xenoStart@@YAXHM@Z ?xenoStart@@YAXHMH@Z ?xenoStart@@YAXXZ ?xenoUpdate@@YAXXZ ?xenoVehicleAccelerate@@YAXHM@Z ?xenoVehicleHandbrake@@YAXH@Z ?xenoVehicleReverse@@YAXH@Z ?xenoVehicleTurn@@YAXHM@Z When I try to use it in another C++ App like this #include <windows.h> class XenoPhysics { private: typedef void (*FunctionFunc)(void); typedef void (*FunctionFuncFloat)(float); typedef void (*FunctionFuncInt)(int); typedef void (*FunctionIntFloatFloatFloat)(int,float,float,float); HMODULE libInstance; public: void LoadLib() { this->libInstance = LoadLibrary(L"F:\\xenophysics.dll"); } void UnloadLib() { FreeLibrary(libInstance); } void xStart() { FunctionFunc curFunc; curFunc = (FunctionFunc)GetProcAddress(this->libInstance, "?xenoStart@@YAXXZ"); curFunc(); } void xEnd() { FunctionFunc curFunc; curFunc = (FunctionFunc)GetProcAddress(libInstance, "xenoEnd"); curFunc(); } void xUpdate() { FunctionFunc curFunc; curFunc = (FunctionFunc)GetProcAddress(libInstance, "xenoUpdate"); curFunc(); } void xMakeRigidBodyStaticBox(int objid) { FunctionFuncInt curFunc; curFunc = (FunctionFuncInt)GetProcAddress(libInstance, "xenoMakeRigidBodyStaticBox"); curFunc(objid); } void xMakeRigidBodyDynamicBox(int objid) { FunctionFuncInt curFunc; curFunc = (FunctionFuncInt)GetProcAddress(libInstance, "xenoMakeRigidBodyDynamicBox"); curFunc(objid); } void xSetRigidBodyPosition(int objid, float x, float y, float z) { FunctionIntFloatFloatFloat curFunc; curFunc = (FunctionIntFloatFloatFloat)GetProcAddress(libInstance, "xenoSetRigidBodyPosition"); curFunc(objid, x, y, z); } void xSetGravity(float grav) { FunctionFuncFloat curFunc; curFunc = (FunctionFuncFloat)GetProcAddress(libInstance, "xenoSetGravity"); curFunc(grav); } }; This is the "wrapper"(or whatever you would call it) class.. To call the functions I'm doing XenoPhysics * d = new XenoPhysics(); d->LoadLib(); d->xStart(); It then throws the following error at me(Note that it passes the LoadLib() without any errors) Unhandled exception at 0x50261bc9 in Xeno Test.exe: 0xC0000005: Access violation reading location 0x00000064. And yes; I've checked that the "curFunc" gets the address, not just a NULL pointer(atleast I think I've checked that).. Anyone who can help out? Edit: Forgot the C#.Net code, how stupid of me :3 Here is the C++ CLR DLL "wrapper" I tried to make: #include <windows.h> // The following ifdef block is the standard way of creating macros which make exporting // from a DLL simpler. All files within this DLL are compiled with the XENOWRAPPERWIN32_EXPORTS // symbol defined on the command line. this symbol should not be defined on any project // that uses this DLL. This way any other project whose source files include this file see // XENOWRAPPERWIN32_API functions as being imported from a DLL, whereas this DLL sees symbols // defined with this macro as being exported. #ifdef XENOWRAPPERWIN32_EXPORTS #define XENOWRAPPERWIN32_API __declspec(dllexport) #else #define XENOWRAPPERWIN32_API __declspec(dllimport) #endif typedef void (*FunctionFunc)(); typedef void (*FunctionFuncFloat)(float); typedef void (*FunctionFuncInt)(int); typedef void (*FunctionIntFloatFloatFloat)(int,float,float,float); // This class is exported from the xeno wrapper win32.dll class XENOWRAPPERWIN32_API Cxenowrapperwin32 { public: Cxenowrapperwin32(void); HINSTANCE libInstance; // FunctionFunc curFunc; // Library base functions void LoadLib() { libInstance = LoadLibrary(L"F:\\xenophysics.dll"); } void UnloadLib() { FreeLibrary(libInstance); } // Function calls to the xeno physics void xStart() { FunctionFunc curFunc; curFunc = (FunctionFunc)GetProcAddress(libInstance, "?xenoStart@@YAXXZ"); curFunc(); } void xEnd() { FunctionFunc curFunc; curFunc = (FunctionFunc)GetProcAddress(libInstance, "?xenoEnd@@YAXXZ"); curFunc(); } void xUpdate() { FunctionFunc curFunc; curFunc = (FunctionFunc)GetProcAddress(libInstance, "?xenoUpdate@@YAXXZ"); curFunc(); } void xMakeRigidBodyStaticBox(int objid) { FunctionFuncInt curFunc; curFunc = (FunctionFuncInt)GetProcAddress(libInstance, "?xenoMakeRigidBodyStaticBox@@YAXH@Z"); curFunc(objid); } void xMakeRigidBodyDynamicBox(int objid) { FunctionFuncInt curFunc; curFunc = (FunctionFuncInt)GetProcAddress(libInstance, "?xenoMakeRigidBodyDynamicBox@@YAXH@Z"); curFunc(objid); } void xSetRigidBodyPosition(int objid, float x, float y, float z) { FunctionIntFloatFloatFloat curFunc; curFunc = (FunctionIntFloatFloatFloat)GetProcAddress(libInstance, "?xenoSetRigidBodyPosition@@YAXHMMM@Z"); curFunc(objid, x, y, z); } void xSetGravity(float grav) { FunctionFuncFloat curFunc; curFunc = (FunctionFuncFloat)GetProcAddress(libInstance, "?xenoSetGravity@@YAXM@Z"); curFunc(grav); } }; extern XENOWRAPPERWIN32_API int nxenowrapperwin32; XENOWRAPPERWIN32_API int fnxenowrapperwin32(void); and here is how I use it in C#.Net class xeno { [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?LoadLib@Cxenowrapperwin32@@QAEXXZ")] public static extern void xLoadLib(); public void LoadLib() { xLoadLib(); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?UnloadLib@Cxenowrapperwin32@@QAEXXZ")] public static extern void xUnloadLib(); public void UnloadLib() { xUnloadLib(); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xStart@Cxenowrapperwin32@@QAEXXZ")] public static extern void xStart(); public void Start() { xStart(); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xUpdate@Cxenowrapperwin32@@QAEXXZ")] public static extern void xUpdate(); public void Update() { xUpdate(); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xEnd@Cxenowrapperwin32@@QAEXXZ")] public static extern void xEnd(); public void End() { xEnd(); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xMakeRigidBodyDynamicBox@Cxenowrapperwin32@@QAEXH@Z")] public static extern void xMakeRigidBodyDynamicBox(int objid); public void MakeRigidBodyDynamicBox(int id) { xMakeRigidBodyDynamicBox(id); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xMakeRigidBodyStaticBox@Cxenowrapperwin32@@QAEXH@Z")] public static extern void xMakeRigidBodyStaticBox(int objid); public void MakeRigidBodyStaticBox(int id) { xMakeRigidBodyStaticBox(id); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xSetGravity@Cxenowrapperwin32@@QAEXM@Z")] public static extern void xSetGravity(float grav); public void SetGravity(float g) { xSetGravity(g); } [DllImport("C:\\Users\\hayer\\Documents\\Visual Studio 2008\\Projects\\xeno wrapper win32\\Debug\\xeno wrapper win32.dll", EntryPoint = "?xSetRigidBodyPosition@Cxenowrapperwin32@@QAEXHMMM@Z")] public static extern void xSetRigidBodyPosition(int obj, float x, float y, float z); public void SetRigidBodyPosition(int id, float q, float w, float e) { xSetRigidBodyPosition(id, q, w, e); } } And in the main C#.Net program I do xeno tx = new xeno(); tx.Start(); tx.SetGravity(-1); tx.MakeRigidBodyStaticBox(ground.Id); tx.MakeRigidBodyDynamicBox(cube.Id); tx.SetRigidBodyPosition(cube.Id, 0, 50, 0);

    Read the article

  • I don't understand how work call_once

    - by SABROG
    Please help me understand how work call_once Here is thread-safe code. I don't understand why this need Thread Local Storage and global_epoch variables. Variable _fast_pthread_once_per_thread_epoch can be changed to constant/enum like {FAST_PTHREAD_ONCE_INIT, BEING_INITIALIZED, FINISH_INITIALIZED}. Why needed count calls in global_epoch? I think this code can be rewriting with logc: if flag FINISH_INITIALIZED do nothing, else go to block with mutexes and this all. #ifndef FAST_PTHREAD_ONCE_H #define FAST_PTHREAD_ONCE_H #include #include typedef sig_atomic_t fast_pthread_once_t; #define FAST_PTHREAD_ONCE_INIT SIG_ATOMIC_MAX extern __thread fast_pthread_once_t _fast_pthread_once_per_thread_epoch; #ifdef __cplusplus extern "C" { #endif extern void fast_pthread_once( pthread_once_t *once, void (*func)(void) ); inline static void fast_pthread_once_inline( fast_pthread_once_t *once, void (*func)(void) ) { fast_pthread_once_t x = *once; /* unprotected access */ if ( x _fast_pthread_once_per_thread_epoch ) { fast_pthread_once( once, func ); } } #ifdef __cplusplus } #endif #endif FAST_PTHREAD_ONCE_H Source fast_pthread_once.c The source is written in C. The lines of the primary function are numbered for reference in the subsequent correctness argument. #include "fast_pthread_once.h" #include static pthread_mutex_t mu = PTHREAD_MUTEX_INITIALIZER; /* protects global_epoch and all fast_pthread_once_t writes */ static pthread_cond_t cv = PTHREAD_COND_INITIALIZER; /* signalled whenever a fast_pthread_once_t is finalized */ #define BEING_INITIALIZED (FAST_PTHREAD_ONCE_INIT - 1) static fast_pthread_once_t global_epoch = 0; /* under mu */ __thread fast_pthread_once_t _fast_pthread_once_per_thread_epoch; static void check( int x ) { if ( x == 0 ) abort(); } void fast_pthread_once( fast_pthread_once_t *once, void (*func)(void) ) { /*01*/ fast_pthread_once_t x = *once; /* unprotected access */ /*02*/ if ( x _fast_pthread_once_per_thread_epoch ) { /*03*/ check( pthread_mutex_lock(µ) == 0 ); /*04*/ if ( *once == FAST_PTHREAD_ONCE_INIT ) { /*05*/ *once = BEING_INITIALIZED; /*06*/ check( pthread_mutex_unlock(µ) == 0 ); /*07*/ (*func)(); /*08*/ check( pthread_mutex_lock(µ) == 0 ); /*09*/ global_epoch++; /*10*/ *once = global_epoch; /*11*/ check( pthread_cond_broadcast(&cv;) == 0 ); /*12*/ } else { /*13*/ while ( *once == BEING_INITIALIZED ) { /*14*/ check( pthread_cond_wait(&cv;, µ) == 0 ); /*15*/ } /*16*/ } /*17*/ _fast_pthread_once_per_thread_epoch = global_epoch; /*18*/ check (pthread_mutex_unlock(µ) == 0); } } This code from BOOST: #ifndef BOOST_THREAD_PTHREAD_ONCE_HPP #define BOOST_THREAD_PTHREAD_ONCE_HPP // once.hpp // // (C) Copyright 2007-8 Anthony Williams // // Distributed under the Boost Software License, Version 1.0. (See // accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) #include #include #include #include "pthread_mutex_scoped_lock.hpp" #include #include #include namespace boost { struct once_flag { boost::uintmax_t epoch; }; namespace detail { BOOST_THREAD_DECL boost::uintmax_t& get_once_per_thread_epoch(); BOOST_THREAD_DECL extern boost::uintmax_t once_global_epoch; BOOST_THREAD_DECL extern pthread_mutex_t once_epoch_mutex; BOOST_THREAD_DECL extern pthread_cond_t once_epoch_cv; } #define BOOST_ONCE_INITIAL_FLAG_VALUE 0 #define BOOST_ONCE_INIT {BOOST_ONCE_INITIAL_FLAG_VALUE} // Based on Mike Burrows fast_pthread_once algorithm as described in // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2444.html template void call_once(once_flag& flag,Function f) { static boost::uintmax_t const uninitialized_flag=BOOST_ONCE_INITIAL_FLAG_VALUE; static boost::uintmax_t const being_initialized=uninitialized_flag+1; boost::uintmax_t const epoch=flag.epoch; boost::uintmax_t& this_thread_epoch=detail::get_once_per_thread_epoch(); if(epoch #endif I right understand, boost don't use atomic operation, so code from boost not thread-safe?

    Read the article

  • problem using pydoc in python

    - by rohanag
    I'm using pydoc in python 2.7.3 to generate documentation for a file called PreProcessingAPI.py which contains a class called PreProcessingAPI In PreProcessingAPI.py, I have the following import in the beginning of the file: from __future__ import division from re import * from nltk.stem import porter The problem is, in the documentation generated by pydoc, nltk.stem.porter is shown as a Module. There is also a DATA heading with all sorts of variables I do not know about. Is there a way to avoid these variables and avoid showing nltk.stem.porter in the modules? I'm running the following command to generate documentation python pydoc.py -w PreProcessingAPI.py I've put the file pydoc.py in the directory containing my file. Here is the file generated: https://www.dropbox.com/s/4rb6ut99o25mwly/PreProcessingAPI.html

    Read the article

  • JavaEE : "Access to default session denied" when sending mail using smtp.gmail.com

    - by Harry Pham
    I am trying to write email authentication feature for my website and I encounter some issues. I got java.lang.SecurityException: Access to default session denied, when I try to do Session.getDefaultInstance. Here are my codes: private static final String SMTP_HOST_NAME = "smtp.gmail.com"; private static final String SMTP_PORT = "465"; private static final String emailSubjectTxt = "Email Confirmation"; private static final String emailFromAddress = "[email protected]"; private static final String SSL_FACTORY = "javax.net.ssl.SSLSocketFactory"; ... String sendTo = "[email protected]"; boolean debug = true; Properties props = new Properties(); props.put("mail.smtp.host", SMTP_HOST_NAME); props.put("mail.smtp.auth", "true"); props.put("mail.debug", "true"); props.put("mail.smtp.port", SMTP_PORT); props.put("mail.smtp.socketFactory.port", SMTP_PORT); props.put("mail.smtp.socketFactory.class", SSL_FACTORY); props.put("mail.smtp.socketFactory.fallback", "false"); //It dies at the next line Session session = Session.getDefaultInstance(props, new javax.mail.Authenticator() { @Override protected PasswordAuthentication getPasswordAuthentication() { return new PasswordAuthentication("myUserName", "myPassword"); } }); session.setDebug(debug); //Set the FROM address Message msg = new MimeMessage(session); InternetAddress addressFrom = new InternetAddress(emailFromAddress); msg.setFrom(addressFrom); //Set the TO address InternetAddress[] addressTo = new InternetAddress[1]; addressTo[0] = new InternetAddress(sendTo); msg.setRecipients(Message.RecipientType.TO, addressTo); //Construct the content of the email confirmation String message = "Test Content" // Setting the Subject and Content Type msg.setSubject(emailSubjectTxt); msg.setContent(message, "text/plain"); Transport.send(msg);

    Read the article

  • WPF - Random hanging with file browser attached behaviour.

    - by Stimul8d
    Hi, I have an attached behavior defined thusly,.. public static class FileBrowserBehaviour { public static bool GetBrowsesOnClick(DependencyObject obj) { return (bool)obj.GetValue(BrowsesOnClickProperty); } public static void SetBrowsesOnClick(DependencyObject obj, bool value) { obj.SetValue(BrowsesOnClickProperty, value); } // Using a DependencyProperty as the backing store for BrowsesOnClick. This enables animation, styling, binding, etc... public static readonly DependencyProperty BrowsesOnClickProperty = DependencyProperty.RegisterAttached("BrowsesOnClick", typeof(bool), typeof(FileBrowserBehaviour), new FrameworkPropertyMetadata(false, new PropertyChangedCallback(BrowsesOnClickChanged))); public static void BrowsesOnClickChanged(DependencyObject obj, DependencyPropertyChangedEventArgs args) { FrameworkElement fe = obj as FrameworkElement; if ((bool)args.NewValue) { fe.PreviewMouseLeftButtonDown += new MouseButtonEventHandler(OpenFileBrowser); } else { fe.PreviewMouseLeftButtonDown -= new MouseButtonEventHandler(OpenFileBrowser); } } static void OpenFileBrowser(object sender, MouseButtonEventArgs e) { var tb = sender as TextBox; if (tb.Text.Length < 1 || tb.Text=="Click to browse..") { OpenFileDialog ofd = new OpenFileDialog(); ofd.Filter = "Executables | *.exe"; if (ofd.ShowDialog() == true) { Debug.WriteLine("Setting textbox text-" + ofd.FileName); tb.Text = ofd.FileName; Debug.WriteLine("Set textbox text"); } } } } It's a nice simple attached behavior which pops open an OpenFileDialog when you click on a textbox and puts the filename in the box when you're done. It works maybe 40% of the time but the rest of the time the whole app hangs. The call stack at this point looks like this - [Managed to Native Transition] WindowsBase.dll!MS.Win32.UnsafeNativeMethods.GetMessageW(ref System.Windows.Interop.MSG msg, System.Runtime.InteropServices.HandleRef hWnd, int uMsgFilterMin, int uMsgFilterMax) + 0x15 bytes WindowsBase.dll!System.Windows.Threading.Dispatcher.GetMessage(ref System.Windows.Interop.MSG msg, System.IntPtr hwnd, int minMessage, int maxMessage) + 0x48 bytes WindowsBase.dll!System.Windows.Threading.Dispatcher.PushFrameImpl(System.Windows.Threading.DispatcherFrame frame = {System.Windows.Threading.DispatcherFrame}) + 0x8b bytes WindowsBase.dll!System.Windows.Threading.Dispatcher.PushFrame(System.Windows.Threading.DispatcherFrame frame) + 0x49 bytes WindowsBase.dll!System.Windows.Threading.Dispatcher.Run() + 0x4c bytes PresentationFramework.dll!System.Windows.Application.RunDispatcher(object ignore) + 0x1e bytes PresentationFramework.dll!System.Windows.Application.RunInternal(System.Windows.Window window) + 0x6f bytes PresentationFramework.dll!System.Windows.Application.Run(System.Windows.Window window) + 0x26 bytes PresentationFramework.dll!System.Windows.Application.Run() + 0x19 bytes Debugatron.exe!Debugatron.App.Main() + 0x5e bytes C# [Native to Managed Transition] [Managed to Native Transition] mscorlib.dll!System.AppDomain.nExecuteAssembly(System.Reflection.Assembly assembly, string[] args) + 0x19 bytes mscorlib.dll!System.Runtime.Hosting.ManifestRunner.Run(bool checkAptModel) + 0x6e bytes mscorlib.dll!System.Runtime.Hosting.ManifestRunner.ExecuteAsAssembly() + 0x84 bytes mscorlib.dll!System.Runtime.Hosting.ApplicationActivator.CreateInstance(System.ActivationContext activationContext, string[] activationCustomData) + 0x65 bytes mscorlib.dll!System.Runtime.Hosting.ApplicationActivator.CreateInstance(System.ActivationContext activationContext) + 0xa bytes mscorlib.dll!System.Activator.CreateInstance(System.ActivationContext activationContext) + 0x3e bytes Microsoft.VisualStudio.HostingProcess.Utilities.dll!Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssemblyDebugInZone() + 0x23 bytes mscorlib.dll!System.Threading.ThreadHelper.ThreadStart_Context(object state) + 0x66 bytes mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state) + 0x6f bytes mscorlib.dll!System.Threading.ThreadHelper.ThreadStart() + 0x44 bytes Now, I've seen this kind of thing before when doing some asynchronous stuff but there's none of that going on at that point. The only thread alive is the UI thread! Also, I always get that last debug statement when it does hang. Can anyone point me in the right direction? This one's driving me crazy!

    Read the article

  • .Net Finalizer Order / Semantics in Esent and Ravendb

    - by mattcodes
    Help me understand. I've read that "The time and order of execution of finalizers cannot be predicted or pre-determined" Correct? However looking at RavenDB source code TransactionStorage.cs I see this ~TransactionalStorage() { try { Trace.WriteLine( "Disposing esent resources from finalizer! You should call TransactionalStorage.Dispose() instead!"); Api.JetTerm2(instance, TermGrbit.Abrupt); } catch (Exception exception) { try { Trace.WriteLine("Failed to dispose esent instance from finalizer because: " + exception); } catch { } } } The API class (which belongs to Managed Esent) which presumable takes handles on native resources presumably using a SafeHandle? So if I understand correctly the native handles SafeHandle can be finalized before TransactionStorage which could have undesired effects, perhaps why Ayende has added an catch all clause around this? Actually diving into Esent code, it does not use SafeHandles. According to CLR via C# this is dangerous? internal static class SomeType { [DllImport("Kernel32", CharSet=CharSet.Unicode, EntryPoint="CreateEvent")] // This prototype is not robust private static extern IntPtr CreateEventBad( IntPtr pSecurityAttributes, Boolean manualReset, Boolean initialState, String name); // This prototype is robust [DllImport("Kernel32", CharSet=CharSet.Unicode, EntryPoint="CreateEvent")] private static extern SafeWaitHandle CreateEventGood( IntPtr pSecurityAttributes, Boolean manualReset, Boolean initialState, String name) public static void SomeMethod() { IntPtr handle = CreateEventBad(IntPtr.Zero, false, false, null); SafeWaitHandle swh = CreateEventGood(IntPtr.Zero, false, false, null); } } Managed Esent (NativeMEthods.cs) looks like this (using Ints vs IntPtrs?): [DllImport(EsentDll, CharSet = EsentCharSet, ExactSpelling = true)] public static extern int JetCreateDatabase(IntPtr sesid, string szFilename, string szConnect, out uint dbid, uint grbit); Is Managed Esent handling finalization/dispoal the correct way, and second is RavenDB handling finalizer the corret way or compensating for Managed Esent?

    Read the article

  • Why can't Java servlet sent out an object ?

    - by Frank
    I use the following method to send out an object from a servlet : public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException { String Full_URL=request.getRequestURL().append("?"+request.getQueryString()).toString(); String Contact_Id=request.getParameter("Contact_Id"); String Time_Stamp=Get_Date_Format(6),query="select from "+Contact_Info_Entry.class.getName()+" where Contact_Id == '"+Contact_Id+"' order by Contact_Id desc"; PersistenceManager pm=null; try { pm=PMF.get().getPersistenceManager(); // note that this returns a list, there could be multiple, DataStore does not ensure uniqueness for non-primary key fields List<Contact_Info_Entry> results=(List<Contact_Info_Entry>)pm.newQuery(query).execute(); Write_Serialized_XML(response.getOutputStream(),results.get(0)); } catch (Exception e) { Send_Email(Email_From,Email_To,"Check_License_Servlet Error [ "+Time_Stamp+" ]",new Text(e.toString()+"\n"+Get_Stack_Trace(e)),null); } finally { pm.close(); } } /** Writes the object and CLOSES the stream. Uses the persistance delegate registered in this class. * @param os The stream to write to. * @param o The object to be serialized. */ public static void writeXMLObject(OutputStream os,Object o) { // Classloader reference must be set since netBeans uses another class loader to loead the bean wich will fail in some circumstances. ClassLoader oldClassLoader=Thread.currentThread().getContextClassLoader(); Thread.currentThread().setContextClassLoader(Check_License_Servlet.class.getClassLoader()); XMLEncoder encoder=new XMLEncoder(os); encoder.setExceptionListener(new ExceptionListener() { public void exceptionThrown(Exception e) { e.printStackTrace(); }}); encoder.writeObject(o); encoder.flush(); encoder.close(); Thread.currentThread().setContextClassLoader(oldClassLoader); } private static ByteArrayOutputStream writeOutputStream=new ByteArrayOutputStream(16384); /** Writes an object to XML. * @param out The boject out to write to. [ Will not be closed. ] * @param o The object to write. */ public static synchronized void writeAsXML(ObjectOutput out,Object o) throws IOException { writeOutputStream.reset(); writeXMLObject(writeOutputStream,o); byte[] Bt_1=writeOutputStream.toByteArray(); byte[] Bt_2=new Des_Encrypter().encrypt(Bt_1,Key); out.writeInt(Bt_2.length); out.write(Bt_2); out.flush(); out.close(); } public static synchronized void Write_Serialized_XML(OutputStream Output_Stream,Object o) throws IOException { writeAsXML(new ObjectOutputStream(Output_Stream),o); } At the receiving end the code look like this : File_Url="http://"+Site_Url+App_Dir+File_Name; try { Contact_Info_Entry Online_Contact_Entry=(Contact_Info_Entry)Read_Serialized_XML(new URL(File_Url)); } catch (Exception e) { e.printStackTrace(); } private static byte[] readBuf=new byte[16384]; public static synchronized Object readAsXML(ObjectInput in) throws IOException { // Classloader reference must be set since netBeans uses another class loader to load the bean which will fail under some circumstances. ClassLoader oldClassLoader=Thread.currentThread().getContextClassLoader(); Thread.currentThread().setContextClassLoader(Tool_Lib_Simple.class.getClassLoader()); int length=in.readInt(); readBuf=new byte[length]; in.readFully(readBuf,0,length); byte Bt[]=new Des_Encrypter().decrypt(readBuf,Key); XMLDecoder dec=new XMLDecoder(new ByteArrayInputStream(Bt,0,Bt.length)); Object o=dec.readObject(); Thread.currentThread().setContextClassLoader(oldClassLoader); in.close(); return o; } public static synchronized Object Read_Serialized_XML(URL File_Url) throws IOException { return readAsXML(new ObjectInputStream(File_Url.openStream())); } But I can't get the object from the Java app that's on the receiving end, why ? The error messages look like this : java.lang.ClassNotFoundException: PayPal_Monitor.Contact_Info_Entry Continuing ... java.lang.NullPointerException: target should not be null Continuing ... java.lang.NullPointerException: target should not be null Continuing ... java.lang.NullPointerException: target should not be null Continuing ...

    Read the article

  • Calculating instantaneous speed and acceleration for a simple Car software model

    - by Dylan
    I am trying to model a speedometer and tachometer for a simple software model of a car dashboard. I want this to be relatively simple, so for my purposes I won't likely simulate variables such as drag (or, assume that drag is a constant). But I would like to know the general formulas for: 1) Calculating the RPM, depending on a position of a graphical slider representing the accelerator. 2) Using this information to find the instantaneous speed (or, magnitude of instantaneous velocity?). I am not sure, in the case of 2), what other independent variables I need to consider. Do I need to consider the frequency of rotation of the wheels (assuming a fixed radius), in addition to the RPM? If anyone can give me a rough explanation plus relevant formulas, or alternatively direct me to other trusted resources online (I have had a hard time sifting through info and determining the accuracy), it would be much appreciated.

    Read the article

  • Multiple values for a specif custom variable in Google Analytics

    - by Nicola Pacini
    we're trying to get rid of a this question : would it be possible to setup more than one value in a custom variable in Google Analytics, at page level ? Eg: _gaq.push(['_setCustomVar',3,'Tag','Custom Variables',3]); We'd like to track most popular tags on a web site who publishes news, articles and stuff. Contents are categorized (each content belongs to one category) and tagged (1 or more tags for each article). So, we'd like to apply this code: _gaq.push(['_setCustomVar',3,'Tag','Custom Variables',3]); _gaq.push(['_setCustomVar',3,'Tag','Google Analytics',3]); in a page that shows an article with these two tags assigned. What do you think? Honestly I didn't find anything in documentation from Google and some other example sites. Many thanks! Nicola

    Read the article

  • Extension methods conflict

    - by Yochai Timmer
    Lets say I have 2 extension methods to string, in 2 different namespaces: namespace test1 { public static class MyExtensions { public static int TestMethod(this String str) { return 1; } } } namespace test2 { public static class MyExtensions2 { public static int TestMethod(this String str) { return 2; } } } These methods are just for example, they don't really do anything. Now lets consider this piece of code: using System; using test1; using test2; namespace blah { public static class Blah { public Blah() { string a = "test"; int i = a.TestMethod(); //Which one is chosen ? } } } I know that only one of the extension methods will be chosen. Which one will it be ? and why ? How can I choose a certain method from a certain namespace ? Edit: Usually I'd use Namespace.ClassNAME.Method() ... But that just beats the whole idea of extension methods. And I don't think you can use Variable.Namespace.Method()

    Read the article

  • Loading Files in AppEngine

    - by Chris M
    I've got a tiny bit of code to display a file in app.yaml - url: /(.*\.(gif|png|jpg)) static_files: static/\1 upload: static/(.*\.(gif|png|jpg)) in main.py ... class ShowImage(webapp.RequestHandler): def get(self): rootpath = os.path.dirname(__file__) file = rootpath + "/static/tracker.gif"; fh=open(file, 'r') self.response.out.write(fh.read()) fh.close ... I can see the files gone up by going to my *.appspot.com/tracker.gif (as per the app.yaml) But using *.appspot.com/showimage returns Traceback (most recent call last): File "/base/python_lib/versions/1/google/appengine/ext/webapp/__init__.py", line 510, in __call__ handler.get(*groups) File "/base/data/home/apps/APPNAME/2.341131266814384624/main.py", line 170, in get fh=open(file, 'r') IOError: [Errno 2] No such file or directory: '/base/data/home/apps/APPNAME/2.341131266814384624/static/tracker.gif'

    Read the article

  • [Java] Nested methods vs "piped" methods, which is better?

    - by Michael Mao
    Hi: Since uni, I've programming in Java for 3 years, although I am not fully dedicated to this language, I have spent quite some time in it, nevertheless. I understand both ways, just curious which style do you prefer. public class Test{ public static void main(String[] args) { System.out.println(getAgent().getAgentName()); } private static Agent getAgent() { return new Agent(); }} class Agent{ private String getAgentName() { return "John Smith"; }} I am pretty happy with nested method calls such like the following public class Test{ public static void main(String[] args) { getAgentName(getAgent()); } private static void getAgentName(Agent agent) { System.out.println(agent.getName()); } private static Agent getAgent() { return new Agent(); }} class Agent { public String getName(){ return "John Smith"; }} They have identical output I saw "John Smith" twice. I wonder, if one way of doing this has better performance or other advantages over the other. Personally I prefer the latter, since for nested methods I can certainly tell which starts first, and which is after. The above code is but a sample, The code that I am working with now is much more complicated, a bit like a maze... So switching between the two styles often blows my head in no time.

    Read the article

  • Exception handling in biztalk 2006 R2

    - by IB
    Hello I have a Biztalk 2006 R2 project (used with ESB Guidance 1) I am calling from orchstration to a static method in c# code, this method uses a class to load a file data into xlang message body at part 0 When i pass filepath which doesnt exists the inside class catch the exception but dont throw it up (in the static method there is a catch block and in the orchstration there is the real handling of the exception) The static method is : public static XLANGMessage LoadFileIntoMessage(XLANGMessage message, string filePath,Encoding encoding) { try { IStreamFactory sf = new FileStreamFactory(filePath,encoding); message[0].LoadFrom(sf); return message; } catch (Exception ex) { throw ex; } } The Class which load the file stream is : private class FileStreamFactory : IStreamFactory { string _fname; Encoding _encoding; public FileStreamFactory(string fname,Encoding encoding) { _fname = fname; _encoding = encoding; } public Stream CreateStream() { try { StreamReader sr; sr = new StreamReader ( _fname, _encoding ); return sr.BaseStream; } catch (Exception ex) { throw ex; } } } I call the static method from the orchstration and expect to catch the exception in my orchstration after the class and the emthod gets it

    Read the article

  • Is Java easy decompilation a factor worth considering

    - by Sandra G
    We are considering the programming language for a desktop application with extended GUI use (tables, windows) and heavy database use. We considered Java for use however the fact that it can be decompiled back very easily into source code is holding us back. There are of course many obfuscators available however they are just that: obfuscators. The only obfuscation worth doing we got was stripping function and variables names into meaningless letters and numbers so that at least stealing code and renaming it back into something meaningful is too much work and we are 100% sure it is not reversible back in any automated way. However as it concerns to protecting internals (like password hashes or sensible variables content) we found obfuscators really lacking. Is there any way to make Java applications as hard to decode as .exe counterparts? And is it a factor to consider when deciding whether to develop in Java a desktop application?

    Read the article

  • AssertionFailure: "null identifier" - FluentNH + SQLServerCE

    - by Stefan
    The code fails at session.Save(employee); with AssertionFailure "null identifier". What am I doing wrong? using FluentNHibernate.Cfg; using FluentNHibernate.Cfg.Db; using FluentNHibernate.Mapping; using NHibernate; using NHibernate.Cfg; using NHibernate.Tool.hbm2ddl; namespace FNHTest { public class Employee { public virtual int Id { get; private set; } public virtual string Name { get; set; } public virtual string Surname { get; set; } } public class EmployeeMap : ClassMap { public EmployeeMap() { Id(e = e.Id); Map(e = e.Name); Map(e = e.Surname); } } public class DB { private static ISessionFactory mySessionFactory = null; private static ISessionFactory SessionFactory { get { if (mySessionFactory == null) { mySessionFactory = Fluently.Configure() .Database(MsSqlCeConfiguration.Standard .ConnectionString("Data Source=MyDB.sdf")) .Mappings(m = m.FluentMappings.AddFromAssemblyOf()) .ExposeConfiguration(BuildSchema) .BuildSessionFactory(); } return mySessionFactory; } } private static void BuildSchema(Configuration configuration) { SchemaExport schemaExport = new SchemaExport(configuration); schemaExport.Execute(false, true, false); } public static ISession OpenSession() { return SessionFactory.OpenSession(); } } public class Program { public static void Main(string[] args) { var employee = new Employee { Name = "John", Surname = "Smith" }; using (ISession session = DB.OpenSession()) { session.Save(employee); } } } }

    Read the article

  • Java method overloading + double dispatch

    - by Max
    Can anybody explain in detail the reason the overloaded method print(Parent parent) is invoked when working with Child instance in my test piece of code? Any pecularities of virtual methods or methods overloading/resolution in Java involved here? Any direct reference to Java Lang Spec? Which term describes this behaviour? Thanks a lot. public class InheritancePlay { public static class Parent { public void doJob(Worker worker) { System.out.println("this is " + this.getClass().getName()); worker.print(this); } } public static class Child extends Parent { } public static class Worker { public void print(Parent parent) { System.out.println("Why this method resolution happens?"); } public void print(Child child) { System.out.println("This is not called"); } } public static void main(String[] args) { Child child = new Child(); Worker worker = new Worker(); child.doJob(worker); } }

    Read the article

  • Javascript Closures - What are the negatives?

    - by vol7ron
    Question: There seem to be many benefits to Closures, but what are the negatives (memory leakage? obfuscation problems? bandwidth increasage?)? Additionally, is my understanding of Closures correct? Finally, once closures are created, can they be destroyed? I've been reading a little bit about Javascript Closures. I hope someone a little more knowledgeable will guide my assertions, correcting me where wrong. Benefits of Closures: Encapsulate the variables to a local scope, by using an internal function. The anonymity of the function is insignificant. What I've found helpful is to do some basic testing, regarding local/global scope: <script type="text/javascript"> var global_text = ""; var global_count = 0; var global_num1 = 10; var global_num2 = 20; var global_num3 = 30; function outerFunc() { var local_count = local_count || 0; alert("global_num1: " + global_num1); // global_num1: undefined var global_num1 = global_num1 || 0; alert("global_num1: " + global_num1); // global_num1: 0 alert("global_num2: " + global_num2); // global_num2: 20 global_num2 = global_num2 || 0; // (notice) no definition with 'var' alert("global_num2: " + global_num2); // global_num2: 20 global_num2 = 0; alert("local_count: " + local_count); // local_count: 0 function output() { global_num3++; alert("local_count: " + local_count + "\n" + "global_count: " + global_count + "\n" + "global_text: " + global_text ); local_count++; } local_count++; global_count++; return output; } var myFunc = outerFunc(); myFunc(); /* Outputs: ********************** * local_count: 1 * global_count: 1 * global_text: **********************/ global_text = "global"; myFunc(); /* Outputs: ********************** * local_count: 2 * global_count: 1 * global_text: global **********************/ var local_count = 100; myFunc(); /* Outputs: ********************** * local_count: 3 * global_count: 1 * global_text: global **********************/ alert("global_num1: " + global_num1); // global_num1: 10 alert("global_num2: " + global_num2); // global_num2: 0 alert("global_num3: " + global_num3); // global_num3: 33 </script> Interesting things I took out of it: The alerts in outerFunc are only called once, which is when the outerFunc call is assigned to myFunc (myFunc = outerFunc()). This assignment seems to keep the outerFunc open, in what I would like to call a persistent state. Everytime myFunc is called, the return is executed. In this case, the return is the internal function. Something really interesting is the localization that occurs when defining local variables. Notice the difference in the first alert between global_num1 and global_num2, even before the variable is trying to be created, global_num1 is considered undefined because the 'var' was used to signify a local variable to that function. -- This has been talked about before, in the order of operation for the Javascript engine, it's just nice to see this put to work. Globals can still be used, but local variables will override them. Notice before the third myFunc call, a global variable called local_count is created, but it as no effect on the internal function, which has a variable that goes by the same name. Conversely, each function call has the ability to modify global variables, as noticed by global_var3. Post Thoughts: Even though the code is straightforward, it is cluttered by alerts for you guys, so you can plug and play. I know there are other examples of closures, many of which use anonymous functions in combination with looping structures, but I think this is good for a 101-starter course to see the effects. The one thing I'm concerned with is the negative impact closures will have on memory. Because it keeps the function environment open, it is also keeping those variables stored in memory, which may/may not have performance implications, especially regarding DOM traversals and garbage collection. I'm also not sure what kind of role this will play in terms of memory leakage and I'm not sure if the closure can be removed from memory by a simple "delete myFunc;." Hope this helps someone, vol7ron

    Read the article

  • Subscribe to the Button's events into a custom control

    - by ThitoO
    Do you know how can I subscribe to an event of the base of my customControl ? I've a custom control with some dependency properties : public class MyCustomControl : Button { static MyCustomControl () { DefaultStyleKeyProperty.OverrideMetadata( typeof( MyCustomControl ), new FrameworkPropertyMetadata( typeof( MyCustomControl ) ) ); } public ICommand KeyDownCommand { get { return (ICommand)GetValue( KeyDownCommandProperty ); } set { SetValue( KeyDownCommandProperty, value ); } } public static readonly DependencyProperty KeyDownCommandProperty = DependencyProperty.Register( "KeyDownCommand", typeof( ICommand ), typeof( MyCustomControl ) ); public ICommand KeyUpCommand { get { return (ICommand)GetValue( KeyUpCommandProperty ); } set { SetValue( KeyUpCommandProperty, value ); } } public static readonly DependencyProperty KeyUpCommandProperty = DependencyProperty.Register( "KeyUpCommand", typeof( ICommand ), typeof( MyCustomControl ) ); public ICommand KeyPressedCommand { get { return (ICommand)GetValue( KeyPressedCommandProperty ); } set { SetValue( KeyPressedCommandProperty, value ); } } public static readonly DependencyProperty KeyPressedCommandProperty = DependencyProperty.Register( "KeyPressedCommand", typeof( ICommand ), typeof( MyCustomControl ) ); } And I whant to subscribe to Button's events (like MouseLeftButtonDown) to run some code in my customControl. Do you know how can I do something like this in the constructor ? static MyCustomControl() { DefaultStyleKeyProperty.OverrideMetadata( typeof( MyCustomControl ), new FrameworkPropertyMetadata( typeof( MyCustomControl ) ) ); MouseLeftButtonDownEvent += (object sender, MouseButtonEventArgs e) => "something"; } Thanks for you help

    Read the article

  • XML validation in Java - why does this fail?

    - by jd
    hi, first time dealing with xml, so please be patient. the code below is probably evil in a million ways (I'd be very happy to hear about all of them), but the main problem is of course that it doesn't work :-) public class Test { private static final String JSDL_SCHEMA_URL = "http://schemas.ggf.org/jsdl/2005/11/jsdl"; private static final String JSDL_POSIX_APPLICATION_SCHEMA_URL = "http://schemas.ggf.org/jsdl/2005/11/jsdl-posix"; public static void main(String[] args) { System.out.println(Test.createJSDLDescription("/bin/echo", "hello world")); } private static String createJSDLDescription(String execName, String args) { Document jsdlJobDefinitionDocument = getJSDLJobDefinitionDocument(); String xmlString = null; // create the elements Element jobDescription = jsdlJobDefinitionDocument.createElement("JobDescription"); Element application = jsdlJobDefinitionDocument.createElement("Application"); Element posixApplication = jsdlJobDefinitionDocument.createElementNS(JSDL_POSIX_APPLICATION_SCHEMA_URL, "POSIXApplication"); Element executable = jsdlJobDefinitionDocument.createElement("Executable"); executable.setTextContent(execName); Element argument = jsdlJobDefinitionDocument.createElement("Argument"); argument.setTextContent(args); //join them into a tree posixApplication.appendChild(executable); posixApplication.appendChild(argument); application.appendChild(posixApplication); jobDescription.appendChild(application); jsdlJobDefinitionDocument.getDocumentElement().appendChild(jobDescription); DOMSource source = new DOMSource(jsdlJobDefinitionDocument); validateXML(source); try { Transformer transformer = TransformerFactory.newInstance().newTransformer(); transformer.setOutputProperty(OutputKeys.INDENT, "yes"); StreamResult result = new StreamResult(new StringWriter()); transformer.transform(source, result); xmlString = result.getWriter().toString(); } catch (Exception e) { e.printStackTrace(); } return xmlString; } private static Document getJSDLJobDefinitionDocument() { DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder builder = null; try { builder = factory.newDocumentBuilder(); } catch (Exception e) { e.printStackTrace(); } DOMImplementation domImpl = builder.getDOMImplementation(); Document theDocument = domImpl.createDocument(JSDL_SCHEMA_URL, "JobDefinition", null); return theDocument; } private static void validateXML(DOMSource source) { try { URL schemaFile = new URL(JSDL_SCHEMA_URL); Sche maFactory schemaFactory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI); Schema schema = schemaFactory.newSchema(schemaFile); Validator validator = schema.newValidator(); DOMResult result = new DOMResult(); validator.validate(source, result); System.out.println("is valid"); } catch (Exception e) { e.printStackTrace(); } } } it spits out a somewhat odd message: org.xml.sax.SAXParseException: cvc-complex-type.2.4.a: Invalid content was found starting with element 'JobDescription'. One of '{"http://schemas.ggf.org/jsdl/2005/11/jsdl":JobDescription}' is expected. Where am I going wrong here? Thanks a lot

    Read the article

  • Issue with deserialization in .Net

    - by Punit Singhi
    I have a class called Test which has four public properties and one of them is static. the problem is after deserialization the static property contains null value. i have debugged the code and found that at server side it contains the value which is a collection , but at client side it becomes null after deserialization. i know static members doesn't serialize and deserialize so obviously it shud contain the value.

    Read the article

  • What is required for a scope in an injection framework?

    - by johncarl
    Working with libraries like Seam, Guice and Spring I have become accustomed to dealing with variables within a scope. These libraries give you a handful of scopes and allow you to define your own. This is a very handy pattern for dealing with variable lifecycles and dependency injection. I have been trying to identify where scoping is the proper solution, or where another solution is more appropriate (context variable, singleton, etc). I have found that if the scope lifecycle is not well defined it is very difficult and often failure prone to manage injections in this way. I have searched on this topic but have found little discussion on the pattern. Is there some good articles discussing where to use scoping and what are required/suggested prerequisites for scoping? I interested in both reference discussion or your view on what is required or suggested for a proper scope implementation. Keep in mind that I am referring to scoping as a general idea, this includes things like globally scoped singletons, request or session scoped web variable, conversation scopes, and others. Edit: Some simple background on custom scopes: Google Guice custom scope Some definitions relevant to above: “scoping” - A set of requirements that define what objects get injected at what time. A simple example of this is Thread scope, based on a ThreadLocal. This scope would inject a variable based on what thread instantiated the class. Here's an example of this: “context variable” - A repository passed from one object to another holding relevant variables. Much like scoping this is a more brute force way of accessing variables based on the calling code. Example: methodOne(Context context){ methodTwo(context); } methodTwo(Context context){ ... //same context as method one, if called from method one } “globally scoped singleton” - Following the singleton pattern, there is one object per application instance. This applies to scopes because there is a basic lifecycle to this object: there is only one of these objects instantiated. Here's an example of a JSR330 Singleton scoped object: @Singleton public void SingletonExample{ ... } usage: public class One { @Inject SingeltonExample example1; } public class Two { @Inject SingeltonExample example2; } After instantiation: one.example1 == two.example2 //true;

    Read the article

  • Using clases in PHP to store function

    - by Artur
    Hello! I need some advise on my PHP code organisation. I need classes where I can store different functions, and I need access to those classes in different parts of my project. Making an object of this classes each time is too sadly, so I've found a two ways have to solve it. First is to use static methods, like class car { public static $wheels_count = 4; public static function change_wheels_count($new_count) { car::$wheels_count = $new_count; } } Second is to use singleton pattern: class Example { // Hold an instance of the class private static $instance; // The singleton method public static function singleton() { if (!isset(self::$instance)) { $c = __CLASS__; self::$instance = new $c; } return self::$instance; } } But author of the article about singletons said, that if I have too much singletons in my code I should reconstruct it. But I need a lot of such classes. Can anybody explain prons and cons of each way? Which is mostly used? Are there more beautiful ways?

    Read the article

  • Discover generic types

    - by vittore
    Thanks @dtb for help, he advised really need piece of code for generic service locator static class Locator { private static class LocatorEntry<T> where T : ... { public static IDataManager<T> instance; } public static void Register<T>(IDataManager<T> instance) where T : ... { LocatorEntry<T>.instance = instance; } public static IDataManager<T> GetInstance<T>() where T : ... { return LocatorEntry<T>.instance; } } However in my previous version I used reflection on assembly to discover a hundred of DataManager's I want to write an method discover like the following void Discover() { var pManager = new ProtocolSQLDataManager(); Register(pManager); var rManager = new ResultSQLDataManager(); Register(rManager); var gType = typeof(ISQLDataAccessManager<>); foreach (Type type in Assembly.GetExecutingAssembly().GetTypes()) { if (type.IsSubclassOf(gType) && !type.IsAbstract)) { var manager = Activator.CreateInstance(type); // put something here in order to make next line of code works Register<T>(manager); } } } How to cast type to appropriate type in order to make Register working( and call appropriate Register ?

    Read the article

< Previous Page | 178 179 180 181 182 183 184 185 186 187 188 189  | Next Page >