我发现静态对象是在加载共享库时 时初始化的。初始化导致构造函数的调用 。 我可以知道任何方式我可以初始化静态对象而不需要 调用构造函数？ 以下是示例编码。 头文件ASURegistrationManager.h #include" ASURegistration。 h" class ASURegistrationManager { public： static ASURegistration& GetASUR管理（）; 私人： 静态ASURegistration ASUReg; //静态对象 ASURegistrationManager（）; ~ASURegistrationManager（）; }; 头文件ASURegistration.h #include" ApplicationInterface.h" class ASURegistration：public IApplicationInterface { public： ASURegistration（）; ~ASURegistration（）; }; 头文件ApplicationInterface.h 类IApplicationInterface { public： IApplicationInterface（ ）; //这将产生线程 ~IApplicationInterface（）; }; ASURegistration.cpp #include" ASURegistration.h" ASURegistration :: ASURegistration（）：IApplicationInterface（） { } ASURegistration :: ~ASURegistration（） { } ASURegistrationManager.cpp #include" ASURegistrationManager.h" ASURegistration ASURegistrationManager :: ASUReg; //这个初始化 调用IApplicationInterface构造函数来创建线程。 ASURegistrationManager :: ASURegistrationManager（） { } ASURegistrationManager :: ~ASURegistrationManager（） { } ASURegistration& ASURegistrationManager :: GetASURegistration（） { return（ASURegistration&）ASUReg; } ApplicationInterface.cpp #include" ApplicationInterface.h" using namespace std; void * APIProcessEvent（void * pvASUInterface）//线程函数 { while（true） { sleep （5）; } 返回（0）; } IApplicationInterface :: IApplicationInterface（） { pthread_t ProcessEventThread; pthread_attr_t attr; cout<< ; 在IApplicationInterface \ n中; if（pthread_attr_init（& attr）！= 0） { std :: cout<<"" pthread_attr_init系统调用线程 failed.\ n" ;; } if（pthread_attr_setscope（& attr，PTHREAD_SCOPE_SYSTE M）！= 0） { std :: cout<<"" pthread_attr_setscope系统调用线程 failed.\" ;; } if（pthread_create（& ProcessEventThread，& attr，APIPro cessEvent，NULL） ！= 0） { std :: cout<<"无法创建Process Event Thread.\ n" ;; } } IApplicationInterface :: ~IApplicationInterface（） { } 我有调用静态方法的cpp函数 ASURegistrationManager :: GetASURegistration（）。 ＃包括< stdio.h> #include" wrap.h" #include" AClass.hpp" #include" CppLibAPI.h" //这只是上面显示的 头文件的组合头文件。 using namespace std; extern" ; C" { void * AClass_new（int x） { ASURegistration& ASUReg = ASURegistrationManager :: GetASURegistration（）; return（（void *）new AClass（x））; // AClass是一个cpp类 } } 以上cpp程序编译为共享库.so将被使用 由C程序。 C程序如下。 #include< stdio.h> #include" wrap.h" int main（void） { printf（" main（）starting\\\"）; 返回0; } 当我运行C程序时，输出如下： 在IApplicationInterface main（）开始 尽可能看到调用了IApplicationInterface构造函数，它将在C main函数之前生成一个线程。在 中的静态方法AClass_new（）cpp函数导致静态 变量ASUReg的初始化，后者又调用IApplicationInterface 构造函数。我需要仅在当时调用cpp函数AClass_new（）时调用线程，而不是在程序期间调用 初始化。还有其他的方法来初始化静态对象 这样没有调用构造函数吗？ 我试图使用静态指针。这不会导致初始化时构造函数的 调用，因为指针可以将初始化为null。但是我关注静态方法' 返回。 如果我将声明更改为 静态ASURegistration * ASUReg 所以ASUReg可以初始化为 ASURegistration * ASURegistrationManager :: ASUReg = NULL; 是以下陈述是否正确？ ASURegistration& ASURegistrationManager :: GetASURegistration（） { return（ASURegistration&）* ASUReg; //这会导致任何问题吗？ } 谢谢！
I have found that the static object is initialised at the time when the shared libary is loaded. The initialisation caused the invocation of the constructor. May I know of any way that I can initialize the static object without invoking the constructor? Below is the sample coding. Header file ASURegistrationManager.h #include "ASURegistration.h" class ASURegistrationManager { public: static ASURegistration& GetASURegistration(); private: static ASURegistration ASUReg; //The static object ASURegistrationManager(); ~ASURegistrationManager(); }; Header file ASURegistration.h #include "ApplicationInterface.h" class ASURegistration : public IApplicationInterface { public: ASURegistration(); ~ASURegistration(); }; Header file ApplicationInterface.h class IApplicationInterface { public: IApplicationInterface(); //This will spawn thread ~IApplicationInterface(); }; ASURegistration.cpp #include "ASURegistration.h" ASURegistration::ASURegistration() : IApplicationInterface() { } ASURegistration::~ASURegistration() { } ASURegistrationManager.cpp #include "ASURegistrationManager.h" ASURegistration ASURegistrationManager::ASUReg; //This initialization invoke the IApplicationInterface constructor to create thread. ASURegistrationManager::ASURegistrationManager() { } ASURegistrationManager::~ASURegistrationManager() { } ASURegistration& ASURegistrationManager::GetASURegistration() { return (ASURegistration &)ASUReg; } ApplicationInterface.cpp #include "ApplicationInterface.h" using namespace std; void *APIProcessEvent(void *pvASUInterface)// Thread Function { while(true) { sleep(5); } return(0); } IApplicationInterface::IApplicationInterface() { pthread_t ProcessEventThread; pthread_attr_t attr; cout << "In IApplicationInterface\n"; if(pthread_attr_init(&attr) != 0) { std::cout<<"pthread_attr_init system call for thread failed.\n"; } if(pthread_attr_setscope(&attr,PTHREAD_SCOPE_SYSTE M) != 0) { std::cout<<"pthread_attr_setscope system call for thread failed.\n"; } if(pthread_create(&ProcessEventThread,&attr,APIPro cessEvent,NULL) != 0) { std::cout<<"Failed to create Process Event Thread.\n"; } } IApplicationInterface::~IApplicationInterface() { } I have the cpp function that calls the static method ASURegistrationManager::GetASURegistration(). #include <stdio.h> #include "wrap.h" #include "AClass.hpp" #include "CppLibAPI.h" //This is just a combination header file of the header files shown above. using namespace std; extern "C" { void * AClass_new(int x) { ASURegistration& ASUReg = ASURegistrationManager::GetASURegistration(); return ((void *)new AClass(x)); //AClass is a cpp class } } The above cpp programs are compiled as a shared library .so to be used by the C program. The C program is as follow. #include <stdio.h> #include "wrap.h" int main(void) { printf("main() starting\n"); return 0; } When I run the C program, the output is as follow: In IApplicationInterface main() starting As you can see the IApplicationInterface constructor is called which will spawn a thread before the C main function. The static method in the AClass_new() cpp function caused the initialisation of the static variable ASUReg which in turns invoke the IApplicationInterface constructor. I need the thread to be spawned only at the point when the cpp function AClass_new() is called instead of during program initialisation. Is there other anyway to initialise the static object such that the constructor is not invoked? I have tried to use a static pointer. That will not cause the invocation of the constructor at initialisation, because a pointer can be initialised to null. But I have concerned on the static method''s return. If I change the declaration to static ASURegistration* ASUReg so ASUReg can be initialised as ASURegistration* ASURegistrationManager::ASUReg=NULL; Is the following statement correct? ASURegistration& ASURegistrationManager::GetASURegistration() { return (ASURegistration &)*ASUReg; //Will this cause any problem? } Thank you!
推荐答案对于上一篇文章感到抱歉，请早点点按发送按钮。 [snip] Sorry about the previous post, hit the send button to early. [snip] 如果我改变了声明静态ASURegistration * ASUReg 所以ASUReg可以初始化为 ASURegistration * ASURegistrationManager :: ASUReg = NULL; 以下是声明正确吗？ ASURegistration& ASURegistrationManager :: GetASURegistration（） {返回（ASURegistration&）* ASUReg; //这会导致任何问题吗？} 谢谢！ If I change the declaration to static ASURegistration* ASUReg so ASUReg can be initialised as ASURegistration* ASURegistrationManager::ASUReg=NULL; Is the following statement correct? ASURegistration& ASURegistrationManager::GetASURegistration() { return (ASURegistration &)*ASUReg; //Will this cause any problem? } Thank you!
上面看起来还可以。你应该删除演员。 ASURegistration& ASURegistrationManager :: GetASURegistration（） { 返回* ASUReg; } john
The above looks OK. You should remove the cast. ASURegistration& ASURegistrationManager::GetASURegistration() { return *ASUReg; } john
Yu < XI ***** @ yahoo>在消息中写道 news：47 ************************** @ posting.google.c om ... Hi, "Yu" <xi*****@yahoo> wrote in message news:47**************************@posting.google.c om... 我发现静态对象在加载共享库时已初始化。初始化导致了构造函数的调用。我可以知道如何在不调用构造函数的情况下初始化静态对象吗？ 下面是样本编码。 头文件ASURegistrationManager.h #include" ASURegistration.h" 类ASURegistrationManager {公开：静态ASURegistration& GetASURegistration（）; 私人：静态ASURegistration ASUReg; //静态对象 ASURegistrationManager（）; ~ASURegistrationManager（）; }; 如下所示，我认为它只会调用构造函数 首次致电GetASURegistration（） class ASURegistrationManager { public： 静态ASURegistration& GetASURegistration（）{ 静态ASURegistration ASUReg; 返回ASUReg; } private： ASURegistrationManager（）; ~ASURegistrationManager（）; }; 谢谢！ I have found that the static object is initialised at the time when the shared libary is loaded. The initialisation caused the invocation of the constructor. May I know of any way that I can initialize the static object without invoking the constructor? Below is the sample coding. Header file ASURegistrationManager.h #include "ASURegistration.h" class ASURegistrationManager { public: static ASURegistration& GetASURegistration(); private: static ASURegistration ASUReg; //The static object ASURegistrationManager(); ~ASURegistrationManager(); }; What about the following, I think it will only invoke the constructor on the first call to GetASURegistration() class ASURegistrationManager { public: static ASURegistration& GetASURegistration() { static ASURegistration ASUReg; return ASUReg; } private: ASURegistrationManager(); ~ASURegistrationManager(); }; Thank you!
> >如果我将声明更改为 > > If I change the declaration to 静态ASURegistration * ASUReg 所以ASUReg可以初始化为 ASURegistration * ASURegistrationManager :: ASUReg = NULL; 以下陈述是否正确？ ASURegistration& ASURegistrationManager :: GetASURegistration（） {返回（ASURegistration&）* ASUReg; //这会导致任何问题吗？} 谢谢！ static ASURegistration* ASUReg so ASUReg can be initialised as ASURegistration* ASURegistrationManager::ASUReg=NULL; Is the following statement correct? ASURegistration& ASURegistrationManager::GetASURegistration() { return (ASURegistration &)*ASUReg; //Will this cause any problem? } Thank you!
以上看起来还可以。你应该删除演员阵容。 ASURegistration& ASURegistrationManager :: GetASURegistration（） {返回* ASUReg; } 约翰
The above looks OK. You should remove the cast. ASURegistration& ASURegistrationManager::GetASURegistration() { return *ASUReg; } john
您好约翰， 上面会崩溃。以下应该是我的问题。谢谢！ ASURegistration& ASURegistrationManager :: GetASURegistration（） { if（！ASUReg） { ASURegistration asuReg = ASURegistration（ ）; ASUReg =& asuReg; } 返回* ASUReg; } Yu :)
Hi John, The above will crash. The following should should my problem. Thanks! ASURegistration& ASURegistrationManager::GetASURegistration() { if (!ASUReg) { ASURegistration asuReg = ASURegistration(); ASUReg = &asuReg; } return *ASUReg; } Yu :)
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初始化静态对象的替代方法。
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