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Date: 3 Jan 92 19:33:57 GMT
From: microsoft!jimad@uunet.uu.net  (Jim ADCOCK)
Subject: Re: Multiple Inheritance
Message-ID: <1992Jan03.193357.17703@microsoft.com>
List-Id: <comp.lang.ada>

In article <4969@charon.cwi.nl> guido@cwi.nl (Guido van Rossum) writes:
|Point taken.  However, I still worry about MI.  When MI is *not* used,
|it still imposes an overhead -- there is a "delta" offset in the vtbl
|that is added to "this" each time a virtual function is called, but
|this delta can only ever be nonzero when MI is used.  I feel that this
|is in direct conflict with the C++ philosophy that language features
|you don't use shouldn't cause overhead.

This is not a language issue, but rather a "quality of implementation"
issue.  C++ compilers exist that don't require the delta in the vtable.