You get an AV because after the call to ReleaseObject, the interface
reference goes out of scope. Delphi then automatically calls _Release on
the interface, but because the implementation object is already freed, you
get an AV.
A better way of doing this is for ReleaseObject to set a flag, and when
_Release is called, it checks the flag to determine whether to free the
object. But this too is dangerous because there may be other references to
the interface and when they go out of scope, _Release will be called.
Why do you want to bypass the reference counting anyway?
Dennis.
----- Original Message -----
From: "Todd Martin" <[EMAIL PROTECTED]>
To: "Multiple recipients of list delphi" <[EMAIL PROTECTED]>
Sent: Wednesday, January 29, 2003 11:11 AM
Subject: [DUG]: Interfaces without reference counting
> Hi. I'm trying to use interfaces in Delphi, but I want to disable
> reference counting. So I created a new class (shown below) with a
> method to free the object, but when I call ReleaseObject() I get an
> access violation after "Free".
> Anyone got any ideas about how I can free the interfaced object when I
> only have a reference to the interface?
>
> Todd
>
> IamUnknown = interface(IUnknown)
> ['{171F7C01-2C89-11D7-815B-2C9E07C10000}']
> procedure ReleaseObject;
> end;
>
> TamInterfacedObject = class(TObject,IamUnknown)
> protected
> function QueryInterface(const IID: TGUID; out Obj): HResult;
> stdcall;
> function _AddRef: Integer; stdcall;
> function _Release: Integer; stdcall;
> procedure ReleaseObject;
> end;
>
> procedure TamInterfacedObject.ReleaseObject;
> begin
> Free;
> end;
>
> function TamInterfacedObject._AddRef: Integer;
> begin
> //do nothing - ignore reference counting
> Result := 0;
> end;
>
> function TamInterfacedObject._Release: Integer;
> begin
> //do nothing - ignore reference counting
> Result := 0;
> end;
>
> --------------------------------------------------------------------------
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