🚀 go-pugleaf

Ed Mulroy [TeamB] wrote:
> A structure definition is a type.  You can then declare or 
> allocate one or more instances of a type.  While for 
> efficiency only one set of physical instructions is 
> generated for a member function of a structure, the manner 
> in which the function is called includes specifying which 
> instance of the type those instructions are to work with. 
> 
> You specified a member function of a structure to Windows 
> as a callback function.  Windows is not party to the 
> internal configuration of your program and has no 
> facilities to call a non static member function in the 
> context of whatever instance of that structure you 
> intended to be used. 
> 
> Only static member functions and normal functions that 
> are not members of a class or structure can be specified
> as callback functions. 
> 
> .  Ed 
> 
> 
>>FireHead wrote:
>>
>>...
>>As you can see that I have function called LRESULT 
>>CALLBACK Events(....) 
>>which globally located.
>>
>>I have function called InitInstance which is part of 
>>Main_Window structure.
>>
>>Where I declare WNDCLASSEX wnd
>>and then I declare the expression
>>as << 
>>   wnd.lpfnWndProc = & sig.Events; 
>>
>>>>I get a error type casting in 
>>
>>the following:
>>
>>Cannot convert 
>>'long (_stdcall *(_closure)(HWND__*,unsigned 
>> int,UINT,long))(HWND__* hwnd,unsigned int,UINT,long)'
>>to 
>>'long (_stdcall *)(HWND__* hwnd,unsigned int,UINT,long)' 
>>in function 
>>struct MainWindow::InitInstance(const char*)
>>
>>Can someone tell me how do I fix this problem.
> 
> 


Hello Ed:

I have got to program because by declaring << struct Signal_Window >> as 
a global object and I created an function such WndProc in this struct.
I was then able initialize the global object in the WinMain and I used 
the WinMain global object(s) address to access all the members and It 
worked.

But my nearly seems remain the same.
Why and should error should disappear when I declare a WndProc function 
as a static function.
I just wanted get an understanding what does this operator <<static>> 
really does.

And yes I did send a copy of this thread in a another forum because I 
not exactlty where to put.

I only have Borland C++ 5.5 Compiler only.

Your Comment:
 > You specified a member function of a structure to Windows
 > as a callback function.  Windows is not party to the
 > internal configuration of your program and has no
 > facilities to call a non static member function in the
 > context of whatever instance of that structure you
 > intended to be used.

If you have got Borland C++ 4.02 or greater and Look for windows 
examples; it exactly contradicts you statement.