Convert OleVariant to Object in Delphi

Question

I\'m working on this project where we don\'t have the source code for large chunks of the project, but we have the .DLL files with some information. There is a bug in the D

Answer 1

Try type cast to IUnknown first.

tempSubclass := Subclass(ParentClass(Integer(IUnknown(oleVariantCast))));

Answer 2

A Dispatch Variant is a pretty generic interface, not a class (which is why it can't be typecast to a Delphi object - it isn't one, and doesn't have the VMT for the class you're trying to cast it to become).

If the DLL contains a type library, you can import that into Delphi and then use the interfaces it contains directly without trying to cast them to anything else first.

If you have documentation about the actual interface implementation in the DLL, you can write a Delphi class that uses that interface. You can convert it by defining a type to represent the interface, and then get access to it using as:

type
  TYourInterface=interface(IDispatch)
    // the interface definition here
  end;

var
  Intf: TYourInterface;
begin
  Intf := YuorOleVariant as TYourInterface;
  // work with interface from DLL using Intf.
  Intf := nil;
end;