Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!rutgers!dptg!ulysses!andante!alice!ark
From: ark@alice.UUCP (Andrew Koenig)
Newsgroups: comp.lang.c++
Subject: Re: copy objects to another location
Message-ID: <9885@alice.UUCP>
Date: 11 Sep 89 12:21:37 GMT
References: <14265@polyslo.CalPoly.EDU>
Distribution: usa
Organization: AT&T Bell Laboratories, Liberty Corner NJ
Lines: 26

In article <14265@polyslo.CalPoly.EDU>, ttwang@polyslo.CalPoly.EDU (Thomas Wang) writes:

> There does not appear to be a portable way to copy an object from one
> memory location to another.  The operator '=' might be overloaded, so
> I cannot depend on it for copying.

Copying an object to a new location presumably means creating
a new object that is a copy of the old one and then deleting
the old object.  To copy an object of class T, use T(const T&);
if that doesn't work, nothing will.  To determine the locations
and handle the memory management, use the memory management stuff
in cfront 2.0.  For example, if `oldloc' and `newloc' point at
the old and new locations, you want to write something like this:

	void* operator new(size_t, void* p) { return p; }

	new(newloc) T (*oldloc);
	oldloc->T::~T();

Now newloc points at a copy of the object and oldloc points at garbage
that should be freed.

None of this works, of course, if the old and new objects overlap.
-- 
				--Andrew Koenig
				  ark@europa.att.com