C / C++ / MFC

error LNK2019: unresolved external symbol "__declspec(dllimport) public: ...

typedef int (MainWindow::*MainWindowPtr)(void);

CallbackWrapperSpecific<MainWindow, MainWindowPtr, int>* cbPtr = new CallbackWrapperSpecific<MainWindow, MainWindowPtr, int>(this, &MainWindow::DoWork);

#ifndef CALLBACKWRAPPER_H
#define CALLBACKWRAPPER_H

#ifdef _EXPORT
#define THREADAPI __declspec(dllexport)
#else
#define THREADAPI __declspec(dllimport)
#endif

template <class Type>
class THREADAPI CallbackWrapperBase
{
public:
	//Functions
	virtual Type Execute() = 0;
};

template <class ClassPtr, class Callback, class Type>
class THREADAPI CallbackWrapperSpecific : public CallbackWrapperBase<Type>
{
public:
	//Functions
	CallbackWrapperSpecific(ClassPtr* pClass, Callback pCallback);

	Type Execute();

	//Members
	ClassPtr* m_classPtr;
	Callback m_callbackPtr;
};

#endif