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POCasting object to interface type with no TInterfacedObject as base class
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copied!<p>I need a class implementing interface with no reference counting. I did the following:</p> <pre><code> IMyInterface = interface(IInterface) ['{B84904DF-9E8A-46E0-98E4-498BF03C2819}'] procedure InterfaceMethod; end; TMyClass = class(TObject, IMyInterface) protected function _AddRef: Integer;stdcall; function _Release: Integer;stdcall; function QueryInterface(const IID: TGUID; out Obj): HResult;stdcall; public procedure InterfaceMethod; end; procedure TMyClass.InterfaceMethod; begin ShowMessage('The Method'); end; function TMyClass.QueryInterface(const IID: TGUID; out Obj): HResult; begin if GetInterface(IID, Obj) then Result := 0 else Result := E_NOINTERFACE; end; function TMyClass._AddRef: Integer; begin Result := -1; end; function TMyClass._Release: Integer; begin Result := -1; end; </code></pre> <p>Lack of reference counting works fine. But my concern is that I cannot cast <code>TMyClass</code> to <code>IMyInterface</code> using <code>as</code> operator:</p> <pre><code>var MyI: IMyInterface; begin MyI := TMyClass.Create as IMyInterface; </code></pre> <p>I am given </p> <blockquote> <p>[DCC Error] E2015 Operator not applicable to this operand type</p> </blockquote> <p>The problem disappears when <code>TMyClass</code> derives from <code>TInterfacedObject</code> - i.e. I can do such casting without compiler error. Obviously I do not want to use TInterfacedObject as a base class as it would make my class reference counted. Why is such casting disallowed and how one would workaround it?</p>

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