I would do the following
Var
Descendant : IFirstDecendant;
Begin
NewObject = TNewClass.Create; //I am going with the assumption that
your
//NewObject is know to be an interfaced object
If (NewObject as
IInterface).QueryInterface(IFirstDescendant,Descendant)=0 then
//Code here for first decendant object
end;
HTH
Ben
-----Original Message-----
From: Todd Martin [mailto:[EMAIL PROTECTED]
Sent: Friday, 13 June 2003 1:53 p.m.
To: Multiple recipients of list delphi
Subject: [DUG]: Interface Inheritance
Hi
Does anyone know if there's a way to test for interface inheritance?
For example
IFirstDescendant = interface(IInterface);
ISecondDescendant = interface(IFirstDescendant);
TNewClass = class(TInterfacedObject,ISecondDescendant);
NewObject = TNewClass.Create;
is there a way to see whether NewObject supports the interface
"IFirstDescendant"
NewObject.GetInterface(IFirstDescendant,Descendant)
returns a nil pointer for Descendant.
I'm thinking the VTable entry for the ISecondDescendant interface, might
link back to IFirstDescendant somehow.
Todd.
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