Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ucsd!rutgers!att!ulysses!andante!alice!ark
From: ark@alice.UUCP (Andrew Koenig)
Newsgroups: comp.lang.c++
Subject: Re: Delete-ing class hierarchie on free store
Keywords: delete, inheritance, free store, base pointer
Message-ID: <9230@alice.UUCP>
Date: 23 Apr 89 11:06:42 GMT
References: <518@atcmpe.atcmp.nl>
Organization: AT&T Bell Laboratories, Liberty Corner NJ
Lines: 20

In article <518@atcmpe.atcmp.nl>, leo@atcmp.nl (Leo  Willems) writes:

> If there are two classes, X and Y, Y derived from X, (both with
> destructors) the destructor Y::~Y() is -not- called in the next situation:

> 	X *x = new Y;		// ok: base pointer assignment
> 	delete x;		// only X::~X() called

> Only the destructor for X is called.

The situation shown above is invalid because x points at a Y,
not an X.  To get this to work properly, either you must write

	delete (Y*) x;

or X must have a virtual destructor.  The virtual destructor route
is recommended if you have any control over the definition of X.
-- 
				--Andrew Koenig
				  ark@europa.att.com