Question

我正在尝试创建线程安全单例类（MySingleton）。 A.h包含声明，而A.cpp具有定义。我需要在都被编译成不同DLL的B.cpp和C.cpp中使用此单例对象。在B.cpp中，我想设置变量ptrval，在C.cpp中，我要检索变量ptrval。

在A.h

class MySingleton {
public:

    static MySingleton* getInstance();
    void setval(int* uid);
    int* getval();


private:
    MySingleton() = default;
    ~MySingleton() = default;
    MySingleton(const MySingleton&) = delete;
    MySingleton& operator=(const MySingleton&) = delete;
    int* ptrval = nullptr;
    static MySingleton* instance;
};

#ifdef MySingleton_DLLEXPORT
extern __declspec(dllexport) int* ptrval = nullptr;
extern __declspec(dllexport) MySingleton* getInstance();
extern __declspec(dllexport) void setval(int* uid);
extern __declspec(dllexport)  int* getval();
extern __declspec(dllexport)  MySingleton* instance = 0;
#else
extern __declspec(dllimport) int* ptrval;
extern __declspec(dllimport) MySingleton* getInstance();
extern __declspec(dllimport) void setval(int* uid);
extern __declspec(dllimport)  int* getval();
extern __declspec(dllimport)  MySingleton* instance;
#endif

在A.cpp中

#pragma push_macro("MySingleton_DLLEXPORT")
#define MySingleton_DLLEXPORT
#include <A.h>
#pragma pop_macro("MySingleton_DLLEXPORT")

MySingleton* MySingleton::instance;

MySingleton*  MySingleton::getInstance()
{
    if (instance == 0)
        instance = new MySingleton();
    return instance;
}

void MySingleton::setval(int* uid) {
    this->ptrval = uid;
}

int* MySingleton::getval() {
    return this->ptrval;
}

在B.cpp中

#pragma push_macro("MySingleton_DLLEXPORT")
#include <A.h>
#pragma pop_macro("MySingleton_DLLEXPORT")

int* uid = (getting uid from a function)
(MySingleton::getInstance())->setval(uid);

在C.cpp中

#pragma push_macro("MySingleton_DLLEXPORT")
#include <A.h>
#pragma pop_macro("MySingleton_DLLEXPORT")

ptrval = (MySingleton::getInstance())->getval();

我收到以下链接错误： B.obj：错误LNK2019：无法解析的外部符号“ public：静态类MySingleton * __cdecl MySingleton :: getInstance（void）”

任何帮助将不胜感激！

在多个文件之间导入/导出单例类

0 个答案: