[fpc-pascal] A better way?

[Ryan Joseph]

> On Apr 14, 2016, at 5:51 PM, Tony Whyman <tony.whyman at mccallumwhyman.com> wrote:
> 
> unit unitA;
> 
> interface
> 
> type
> 
> class TClassA
> private
>  FClassBObject: TObject;
> public
>  procedure SomeProc;
> end;
> 
> implementation
> 
> uses unitB;
> 
> Maybe I’m doing something stupid but other languages have forward declarations so I wonder why Pascal isn’t doing this also since it seems like the obvious solution.
> 
> 
> procedure TClassA.SomeProc;
> begin
>  TClassB(FClassBObject).OtherProc;
> end;
> 
> end.
> 
> unitB is pretty similar.
> 
> As long as you make sure that FClassBObject really is a TClassB object when it is assigned, the above should all work. The only extra effort is with the TClassB(...) wrapper for each reference to FClassBObject.

I use forward declarations sometimes but of course they need to be in the same block so they don’t solve this problem.

Yeah type casting. :) Like interfaces they work but they add a significant overhead and clutter (especially if they need to be used with dozens of methods in a unit) so that’s why I’m seeing if there’s a better way. However I think I like your idea of using them in conjunction with the uses in the implementation instead of my "abstract class" solution. Thanks for the tip.

Regards,
	Ryan Joseph