Casting a delphi interface to its implementation class without modifying the interface [duplicate]

Answer 1

• The classic take on this is by Hallvard Vassbotn: Hack #7: Interface to Object
• More recently Barry Kelly, a Delphi compiler engineer, also provided an implementation: An ugly alternative to interface to object casting

I think both approaches should work.

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Incidentally, does anyone know if Hallvard is still active? I've not come across him in the past few years.