What is a MFC class that supports dynamic creation?

Dynamic creation of Object

MFC/C++ uses new operator to create an object from a constant type at runtime. MFC supports dynamic creation of object using type with runtime type identification support. DYNCREATE macro pair is used for this purpose.

DECLARE_DYNCREATE

This macro enables objects of CObject-derived classes to be created dynamically at run time. Ths is used in the declaration part of the class and thus can be added in .h file.

Syntax

DECLARE_DYNCREATE(class_name)
/* class_name = The actual name of the class.*/

IMPLEMENT_DYNCREATE

Enables objects of CObject-derived classes to be created dynamically at run time when used with the DECLARE_DYNCREATE macro. Ths is used in the implementation part of the class and thus can be added in .h file.

Syntax

IMPLEMENT_DYNCREATE(class_name, base_class_name )
/* class_name = The actual name of the class.
   base_class_name = Base class name.
 */

DYNCREATE Example

class CMyDynCreateObj : public CObject
{
     int m_Num;
public:
     DECLARE_DYNCREATE(CMyDynCreateObj)
     CMyDynCreateObj(int Num) { m_Num = Num; }
private:
     CMyDynCreateObj() { m_Num = 0; } 
};

IMPLEMENT_DYNCREATE(CMyDynCreateObj, CObject)

void TestCreateObject(void)
{
  CRuntimeClass* prt = RUNTIME_CLASS(CAge);
  ASSERT(strcmp(prt->m_lpszClassName, "CAge") == 0);
}

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