EXPORT for window procedures

[Keith Waters]

I note that the window procedure in SKELETON.BAS is defined with the EXPORT keyword as follows.

FUNCTION WndProc (BYVAL hWnd AS LONG, BYVAL wMsg AS LONG, _
                  BYVAL wParam AS LONG, BYVAL lParam AS LONG) EXPORT AS LONG

Is EXPORT needed here? Also, similar considerations apply to sub-classing window procedures. I’ve just stripped all EXPORT’s from my exe, which makes extensive use of subclassing, and it seems to still run just fine.

Keith


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[Lance Edmonds]

In this case they are not needed since you pass the CODEPTR of the WinProc to the required API (ie, via RegisterClass, CreateDialog, etc), so Windows performs a direct call to the memory location.

Likewise, the CALL clause in a CONTROL ADD statement performs the same action internally, so CALLBACK FUNCTIONs do not need to be EXPORTed either.



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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Keith Waters]

Thanks Lance. That's cleared that for me.
Keith

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[Kev Peel]

I think the EXPORT for window procedures was a 16 bit requirement

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Kev G Peel
KGP Software, Bridgwater, UK.
mailto:[email protected][email protected]</A>