[fpc-devel] Generics

[Mattias Gaertner]

On Fri, 17 Aug 2007 10:20:13 +0200 (CEST)
Michael Van Canneyt <michael at freepascal.org> wrote:

>[...]
> > > > > What local types are/will be allowed?
> > > > >
> > > > > For example, this is currently not allowed:
> > > > >
> > > > >   generic TTree<T> = class(TObject)
> > > > >   type public   TTreeNode = specialize TNode<T>;
> > > > >   end;
> > > > >
> > > > > And this neither:
> > > > >
> > > > >   generic TTree<T> = class(TObject)
> > > > >   type public
> > > > >     TTreeNode = class
> > > > >       Data: T;
> > > > >     end;
> > > > >   end;
> > > > >
> > > > >
> > > > > OTOH records and pointers are allowed.
> > > > > Will this stay, or is this just not yet implemented?
> > > > Is there a need to support this?

I don't need them.
I'm just asking for the codetools.
So I guess the answer is: Will stay. (read: there are no
further plans).


> > > Well, it seems rather strange that the type block would not allow
> > > all possible types.
> > 
> > Only a few types can be generic as well. Nested classes cause a lot
> > of hidden pitfalls, that's why they aren't allowed.
> 
> OK, probably I should add this to the docs. I assume all types can be
> defined except classes and generics ?

.. and objects and interfaces.

It seems generic objects and interfaces are allowed, but this
is not yet documented.

What about generic records? Will they be implemented?


Mattias