[fpc-pascal]Method in WndClassEX
Jonas Maebe
jonas at zeus.rug.ac.be
Fri Oct 12 15:53:25 CEST 2001
On donderdag, oktober 11, 2001, at 07:02 , Luis Del Aguila wrote:
> may I allocate a metthod in the field lpfnWndProc of the WndClassEX
> Registers?
> Like this :
>
> VAR
> ClaseVentana : WndClassEX;
> ...
>
> ClaseVentana.lpfnWndProc := WndProc(Método);
No, you cannot assign methods to normal procedure variables, only normal
procedures. The reason is that methods always expect an extra parameter
containing the self pointer of the object/class instance they are
working on. If you do the above, then when windows calls you "wndproc"
(which isn't really a wndproc, since you have to add an explicit type
cast for the compiler to accept the statement), it won't pass any self
pointer and as such the method will not work correctly.
Jonas
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