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- Xref: sparky comp.lang.c++:11403 comp.std.c++:922
- Newsgroups: comp.lang.c++,comp.std.c++
- Path: sparky!uunet!mole-end!mat
- From: mat@mole-end
- Subject: Re: Language extensions for run-time type identification
- Message-ID: <1992Jul22.091752.22521@mole-end>
- Organization: :
- References: <14ft2uINNjh4@agate.berkeley.edu> <1992Jul21.143131.6902@cadsun.corp.mot.com>
- Date: Wed, 22 Jul 1992 09:17:52 GMT
- Lines: 24
-
- Just a point of fact:
-
- In article <1992Jul21.143131.6902@cadsun.corp.mot.com>, shang@corp.mot.com (David (Lujun) Shang) writes:
-
- > > In most implementations of classes with virtual functions, each object
- > > already has, in effect, a type-ID: the pointer to the virtual function
- > > table. This is a natural hook on which to hang run time type checking.
-
- > The pointer to vtable can not work as a type-ID for a language with multiple
- > inheritance. An object of particular class derived from multiple bases may
- > contain serveral different vtable references. Different base pointers to the
- > same object may use different vtable pointers.
-
- Not quite true. Those multiple vtable references in a complete object
- all have to point to vtables whose only differences are their `offset
- adjustments.'
-
- This area has been studied to death and is being studied right now into
- the twilight zone and while some problems remain, this is not one of them.
- --
- (This man's opinions are his own.)
- From mole-end Mark Terribile
-
- uunet!mole-end!mat, Somewhere in Matawan, NJ
-