Florian Klaempfl wrote:
Mattias Gaertner schrieb:
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?
Imho the example given by Mattias demonstrates that a similar construct would
be desirable; or is there another way to accommodate for the aggregation of
generic classes?
I think TTree/TNode is a typical example where you'd like to use the generic
type used for TTree to create the corresponding TNode.
type
generic TNode<T> = class
type TChildList = TList<TNode>; // and how about this?
Data:T;
Children:TChildList;
end;
generic TTree<T> = class
type TTreeNode = specialize TNode<T>;
Root:TTreeNode;
GetNode(Index:integer):TTreeNode;
GetNodeData(Index:integer):T;
end;
...
function TTree.GetNodeData(Index:integer):T;
begin
Result:=GetNode(Index).Data;
end;
Regards,
Bram
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