AFX_DATA是什么意思？有什么用？

[cl007]

是什么意思？

[kunjun_oy]

便于ClassWizard读写数据。

[Probe1_0]

ClassWizard and AppWizard insert specially formatted comment delimiters in your source code files to mark the places in your files that ClassWizard can write to. AFX_DATA is used to mark the beginning and end of member variable declarations in your header file (.H) used for dialog data exchange (DDX):

//{{AFX_DATA(classname)
...
//}}AFX_DATA

[Probe1_0]

ClassWizard and AppWizard insert specially formatted comment delimiters in your source code files to mark the places in your files that ClassWizard can write to. AFX_DATA is used to mark the beginning and end of member variable declarations in your header file (.H) used for dialog data exchange (DDX):

//{{AFX_DATA(classname)
...
//}}AFX_DATA

[蒋晟]

HOWTO: Use _declspec(dllexport) in an MFC Extension DLL

Q128199


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The information in this article applies to:

The Microsoft Foundation Classes (MFC), used with:
Microsoft Visual C++, 32-bit Editions, versions 2.0, 2.1, 4.0

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For example, the DECLARE_DYNAMIC macro is defined as follows when building an extension DLL:

#define DECLARE_DYNAMIC(class_name) \
protected: \
static CRuntimeClass* PASCAL _GetBaseClass(); \
public: \
static AFX_DATA CRuntimeClass class##class_name; \
virtual CRuntimeClass* GetRuntimeClass() const; \
The line that begins "static AFX_DATA" is declaring a static object inside of your class. To export this class correctly and access the run-time information from a client .EXE, you need to export this static object. Because the static object is declared with the modifier AFX_DATA, you only need to define AFX_DATA to be _declspec(dllexport) when building your DLL and define it as _declspec(dllimport) when building your client executable. As discussed above, AFX_EXT_CLASS is already defined in this way. So you just need to re-define AFX_DATA to be the same as AFX_EXT_CLASS around your class definition.

For example:

#undef AFX_DATA
#define AFX_DATA AFX_EXT_CLASS

class CExampleView : public CView
{

DECLARE_DYNAMIC()
// ... class definition ...

};

#undef AFX_DATA
#define AFX_DATA
MFC always uses the AFX_DATA symbol on data items it defines within its macros, so this technique will work for all such scenarios. For example it will work for DECLARE_MESSAGE_MAP.

NOTE: if you are exporting the entire class rather than selected members of the class, static data members are automatically exported.