[fpc-devel] comparing methods

[Thaddy]

Mattias Gärtner wrote:
> Hi,
>
> Can someone explain why in mode objfpc comparing methods only compares 
> the address, but not the instance?
> For example:
>
>   a:=TMyClass.Create;
>   b:=TMyClass.Create;
>   if @a.test = @b.test then writeln('the same method');
>
> This results in strange behaviors, when using the following code (from 
> the FCL):
>
> property AfterConnect: TNotifyEvent read FAfterConnect write 
> SetAfterConnect;
>
> procedure TCustomConnection.SetAfterConnect(const AValue: TNotifyEvent);
> begin
>   if FAfterConnect=AValue then exit;
>   FAfterConnect:=AValue;
> end;
>
>
> Mattias
>
>
> _______________________________________________
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> http://lists.freepascal.org/mailman/listinfo/fpc-devel
>
The deep copy versus shallow copy problem.
Depending on what you want. here it is implementing a deep compare, (an 
instance full copy) instead of a shallow compare (a pointer copy). Both 
are valid paradigms, but also -very, very - basic computer science. You 
for some reason want a shallow compare, which may or may not be correct, 
depending on your code.