带有静态实例的未定义​​引用 [英] undefined reference with a static instance

问题描述

我目前正在将一些代码从Visual Studio移植到Mingw GCC. 当我尝试使用静态变量时，似乎出现了问题. 这段代码在Visual Studio中可以正常工作，所以我不确定这里可能是什么问题.我已经粘贴了代码外观的概述.如果这还不够的话，我可以投入更多.

I am currently porting some code from Visual Studio to Mingw GCC. It seems there is a problem when I attempt to use a static variable . This code works fine in Visual studio so I am not sure what the problem might be here. I have pasted an outline of what the code looks like. If this is insufficient I could put in more.

Header file: .h
namespace LG_Wrapper
{
    template <LG_Thread Thread>
    class EffectApplication : public ktApplication
    {
    public:
    static EffectApplication<Thread>& GetInstance();
    protected:
        .....
        .....
        static boost::recursive_mutex mResource;
      }
}

DECLARE_LEGACY_TYPES(EffectApplication);


Source File: .cpp
namespace LG_Wrapper
{

    template<>
    boost::recursive_mutex  EffectApplication<LG_Thread_NAME>::mResource;  //LG_Thread_NAME type discussed below

    template <LG_Thread Thread>
    EffectApplication<Thread>& EffectApplication<Thread>::GetInstance()
    {
        boost::recursive_mutex::scoped_lock mutex( mResource ); //Error with mResource

        static EffectApplication<Thread> instance;
        return instance;
    }
    ....
}

现在我不确定LG_Thread_NAME类型. 看完代码后，我注意到我在项目设置中定义了以下内容

Now I am not sure about the LG_Thread_NAME type. After going through the code I noticed that I define the following in the project settings

LG_THREAD_NAME=GAME

此定义在代码中的其他地方与该宏一起起作用

This definition comes into play with this macro somewhere else in the code

#define DECLARE_LEGACY_TYPES(...)

我在访问mResource时遇到问题，如果我注释掉该语句，代码可以正常运行

I am having issue accessing mResource The code builds fine if I comment out the statement

boost::recursive_mutex::scoped_lock mutex( mResource );

关于上述代码为什么会出现以下错误的任何建议?

Any suggestions on why I might be getting the following error with the above code ?

(.text$_ZN10KT_Wrapper17EffectApplicationILNS_9LT_ThreadE0EE11GetInstanceEv[_ZN10LT_Wrapper17EffectApplicationILNS_9LT_ThreadE0EE11GetInstanceEv]+0x11): undefined reference to `LT_Wrapper::EffectApplication<(LT_Wrapper::LT_Thread)0>::mResource'

更新: 我肯定变量mResource存在问题，因为在静态方法中.如果我这样做，它将建立良好的状态

Update: I am certain that there is something wrong with the variable mResource because in the static method. If I do this it builds fine

  boost::recursive_mutex l;
boost::recursive_mutex::scoped_lock mutex( l );

问题重复: 我不确定这个问题如何与所提供的链接重复.在提供的所有链接中，操作尚未初始化其静态变量.在这里，我在类之外初始化了我的静态变量.

Duplicate Question Issue: I am not sure how this question is a duplicate of the links provided. In all the links provided the ops have not initialized their static variables. Here I have initialized my static variable outside the class.

推荐答案

初始化

template<>
boost::recursive_mutex  EffectApplication<LG_Thread_NAME>::mResource;

仍然不正确，因为不是针对所有模板参数初始化mResource，而是仅针对LG_Thread_NAME的特殊化而初始化.因此，我想当您尝试使用其他模板参数访问它时，您会遇到错误.

still is not correct, since you initialize mResource not for all template parameter, but only for specialization with LG_Thread_NAME. So I guess when you try to access it with some another template parameter you've got an error.

正确的方法是这样

template<LG_Thread Thread>
boost::recursive_mutex  EffectApplication<Thread>::mResource;

我也不确定我的答案，因为该错误表明问题出在LT_Wrapper类，模板参数(LT_Wrapper::LT_Thread)0对我来说很奇怪.

Also I'm not sure with my answer because the error says that the problem is with LT_Wrapper class and template parameter (LT_Wrapper::LT_Thread)0 looks strange to me.

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