Thanks. That confirms my own more recent thoughts on this.
Todd.
----- Original Message -----
From: "Dennis Chuah" <[EMAIL PROTECTED]>
To: "Multiple recipients of list delphi" <[EMAIL PROTECTED]>
Sent: Wednesday, 29 January 2003 15:41
Subject: Re: [DUG]: Interfaces without reference counting
>
> 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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