此宏IMPLEMENT_DYNCREATE的宏定义表示什么?

问题描述

做什么此代码执行???

#define IMPLEMENT_DYNCREATE(class_name，base_class_name)\
CObject * PASCAL class_name :: CreateObject()\
{返回新的class_name; } \
#define IMPLEMENT_DYNCREATE(class_name，base_class_name)\
CObject * PASCAL class_name :: CreateObject()\
{返回新的class_name; } \
IMPLEMENT_RUNTIMECLASS(class_name，base_class_name，0xFFFF，\
class_name :: CreateObject，NULL)

what does the
this code performs???

#define IMPLEMENT_DYNCREATE(class_name, base_class_name) \
CObject* PASCAL class_name::CreateObject() \
{ return new class_name; } \
#define IMPLEMENT_DYNCREATE(class_name, base_class_name) \
CObject* PASCAL class_name::CreateObject() \
{ return new class_name; } \
IMPLEMENT_RUNTIMECLASS(class_name, base_class_name, 0xFFFF, \
class_name::CreateObject, NULL)

推荐答案

// In class Declaration (.h) 
class A : public CObject
{
	DECLARE_DYNCREATE( A )
};

//In class implementation( .cpp)
IMPLEMENT_DYNCREATE( A, CObject )

在运行时，它们会扩展并变为如下所示.这只是一个模拟，以了解其背后的概念

During run time these gets expanded and become as shown below. This is just a simulation to understand the concept behind it

In class Declaration (.h) 
class A : public CObject
{
	static CObject* PASCAL CreateObject();
protected:
	static CRuntimeClass* PASCAL _GetBaseClass();
public:
	static const AFX_DATA CRuntimeClass classA;
	virtual CRuntimeClass* GetRuntimeClass() const;
};
/* it declares 3 functions CreateObject(),GetBaseClass(),GetRuntimeClass() and one data member classA of type CRuntimeClass structure*/

//In class implementation( .cpp)

// Remember classA is static. so initialized as below
A::classA.m_lpszClassName = "A";
A::classA.m_nObjectSize = sizeof( A );
A::classA.m_wSchema = 0xFFFF;
A::classA.m_pfnCreateObject = A::CreateObject; // Function pointer
A::classA.m_pfnGetBaseClass =A:: _GetBaseClass; // Function pointer
A::m_pNextClass = NULL;

CObject* PASCAL A::CreateObject() 
{ 
return new A;
} 
CRuntimeClass* A::GetRuntimeClass() const 	
{ 
return RUNTIME_CLASS( A ); 
}
CRuntimeClass* PASCAL A::_GetBaseClass()
{
return RUNTIME_CLASS(CObject); 
}

要了解更多信息，请参见msdn中的CRuntimeClass()，RUNTIME_CLASS等.

to understand more see what is CRuntimeClass(), RUNTIME_CLASS etc in msdn

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