Path: utzoo!censor!geac!torsqnt!hybrid!scifi!bywater!uunet!tdatirv!sarima
From: sarima@tdatirv.UUCP (Stanley Friesen)
Newsgroups: comp.lang.c++
Subject: Re: Calling virtuals from destructors
Message-ID: <84@tdatirv.UUCP>
Date: 15 Jan 91 15:48:41 GMT
References: <424@nec-gw.nec.com>
Reply-To: sarima@tdatirv.UUCP (Stanley Friesen)
Distribution: na
Organization: Teradata Corp., Irvine
Lines: 32

In article <424@nec-gw.nec.com> stuart@NECAM.tdd.sj.nec.com (Stuart Palmer) writes:
>
>If you call a virtual member function from a destructor, what is
>the behavior?
 
>In Sun 2.0, if you call a virtual member function from
>a destructor, the "actual" virtual function that is compiled into
>the class vtbl will not get called.  Rather, the virtual function
>at the class level where the call was made gets called.

This is correct, at least for version 2.XC++.
This is so because by the time a destructor is called all derived classes
have been destroyed, so the object is no longer a derived class object.
Thus the destuctor can make a 'static' call to the function.


>This is different than Glockenspiel 1.2.  1.2 calls the virtual
>function from the vtbl (as might be expected?).

This is (or would be) wrong for a 2.X compiler, but it may be that as a 1.2
compiler this was correct at the time.  (I.e. this could be something that
changed between version 1.2 and 2.0 of cfront).

>Is this a bug in one of the compilers?

It is either a bug or an archaism in the Glockenspiel compiler.


By the way, this should probably be in the FAQ, it has been asked enough.
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uunet!tdatirv!sarima				(Stanley Friesen)