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From: shankar@hpclisp.HP.COM (Shankar Unni)
Newsgroups: comp.lang.c++
Subject: Re: virtual base classes
Message-ID: <58170003@hpclisp.HP.COM>
Date: 2 Jan 90 21:02:07 GMT
References: <8059@cbnewsm.ATT.COM>
Organization: Hewlett-Packard Calif. Language Lab
Lines: 38

> 
>               A   A       <<< ********** revised drawing
> 	       /    | 
>    virtual  /     | 
> 	     /      | 
> 	    B       C
> 	     \     /
> 	      \   /  virtual
> 	       \ /
> 	        D
> 
> 
>    (a) there is only *one* A in D.
> 
> *****> no, look again -- there are two, one within the C sub-object
>        of D and the virtual OA instance:

Yeah, I looked at the generated code, but it seemed to me that one of the
subobjects was not being used. So I jumped to the conclusions that I
posted. Hmm, I suppose I should read the generated code a little more
carefully.

> *****> cfront actually has a bug in that it is
>        choosing the instance associated with the
>        virtual object associated with B -- it should
>        be ambiguous and will be fixed in 2.1
> 
> 	d . PA-> a_mem__1A = 1 ;  // generated cfront
> 

Right - that's what I saw, but I tried to diagnose the problem too soon and
jumped to the wrong conclusion.


Thanks for the clarification.
-------
Shankar Unni.
HP/California Language Lab.