Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!uw-beaver!fluke!ssc-vax!dmg
From: dmg@ssc-vax.UUCP (David Geary)
Newsgroups: comp.lang.c++
Subject: What is C++ doing?
Keywords: behind my back in C, that is...
Message-ID: <2671@ssc-vax.UUCP>
Date: 19 May 89 16:10:27 GMT
Organization: Boeing Aerospace Corp., Seattle WA
Lines: 39

In article <11549@ulysses.homer.nj.att.com>, Jerry Schwarz writes:

+ No. And in 2.0 the default behavior never copies the _vptr. The _vptr
+ is associated with an object when the object is allocated and cannot
+ be changed. Copying the _vptr "breaks" the C++ type system.

  I've been using C for a long time (well, 5 years anyway), and I am
just starting to jump into C++.  I've read BS ;-), and also another
book - "C++ Programming", by John Berry, and have played around with
creating some classes for the past week or so.

  I think I have a pretty good handle on the basics of oop and C++,
but what I'd like to know is *how* C++ is implemented.  I have
Glockenspiel C++ on an Apollo, but I don't know how to get the
"compiler" to let me see it's C output.  (Anybody know?)

  Anyway, Jerry's posting is a perfect example of my ignorance ;-).
What *is* a _vptr?  I have also heard reference to the VTABLE
in previous postings.  What are these animals?

  Of course, I don't expect anybody to describe everything that
cfront does, but it'd sure give me more understanding of C++ if
I knew what it was doing *behind my back* in C.

Thanks...

*************************************************************************
"The dog up and died, he up and died.  After 20 years, he still grieves"

	       Mr. Bojangles, Nitty Gritty Dirt Band
*************************************************************************



-- 
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~ David Geary, Boeing Aerospace, Seattle                 ~ 
~ "I wish I lived where it *only* rains 364 days a year" ~
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