Newsgroups: comp.lang.c++
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From: ahodgson@athena.mit.edu (Antony Hodgson)
Subject: How do you copy a Derived object?
Message-ID: <1991Mar26.152847.5853@athena.mit.edu>
Sender: news@athena.mit.edu (News system)
Organization: Massachusetts Institute of Technology
Date: Tue, 26 Mar 91 15:28:47 GMT
Lines: 20


Suppose I have a function, void f( Base& b ), and inside f() I want to
make a local copy of whatever b is.  Since b could actually be a derived
class, I can't simply do the following:

void f( Base& b )
    {	Base B(b);  ...  }

nor can I do

void f( Base& b )
    {   Base* B = new Base( b ); ...  }

What I really need to do is something like Base* B = new (typeof(b))(b).
Is this possible?  Thanks in advance for any help.  Email replies are fine.

Tony Hodgson
ahodgson@hstbme.mit.edu