> On Apr 14, 2016, at 2:56 PM, Graeme Geldenhuys
> <mailingli...@geldenhuys.co.uk> wrote:
>
> If you can give an actual example we can help. I've used TP then Delphi
> and now Free Pascal for more than 20+ years. I can probably count on one
> hand how many circular reference issues I had. So I dont' think it is
> such a big problem as you make out.
>
> Often moving uses clause references from the Interface section to the
> Implementation section solve the problem. Sometimes using a base class
> in the interface works. Sometimes using Interfaces (the language
> feature) is a much better approach.
>
> So again, if you can give an actual example of the various units, and
> how they relate (use each other), then we might be able to help you further.
>
> Regards,
> Graeme
I’ve just browsed over some code and found moving uses to the implementation
did in fact help. That’s really helpful thank you both. However I’m still
seeing some common patterns which just don’t seem Pascal friendly. I started
using these more often after using Objective-C on Mac frequently and I really
like it but it requires me to hack around the compiler in Pascal.
In that example below the “main” class has children it talks to using an
interface and returning a reference to itself for introspection. They are
interdependent but Pascal doesn’t offer a way to expose a global namespace for
both the units as far as I know. In other languages I would make another
“globals” unit and keep forward references to TClassA, TClassB and IClassA.
==============================
ClassB.pas:
uses
ClassA; // <----- circular reference but I need to know about ClassA
type
TClassB = class (IClassA)
// when we implement this method we may need to know some things
// about the parent (TClassA) so it must be included
procedure ClassDidThis (parent: TClassA; action: integer);
end;
ClassA.pas:
uses
ClassB;
type
TClassA = class
child: TClassB;
end;
// TClassA uses this interface to talk with it's “children” (TClassB)
// and always returns a reference to itself because the children
// often need to know about the parent also
IClassA = interface
procedure ClassDidThis (parent: TClassA; action: integer);
end;
Regards,
Ryan Joseph
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