Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!decwrl!infopiz!lupine!rfg
From: rfg@NCD.COM (Ron Guilmette)
Newsgroups: comp.lang.c++
Subject: Re: Smart Pointers Aren't Enough
Keywords: garbage collection, smart pointers, frustration
Message-ID: <3780@lupine.NCD.COM>
Date: 8 Feb 91 04:33:31 GMT
References: <11707@darkstar.ucsc.edu>
Organization: Network Computing Devices, Inc., Mt. View, CA
Lines: 34

In article <11707@darkstar.ucsc.edu> daniel@terra.ucsc.edu (Daniel Edelson) writes:
+
+Case in point:
+
+	struct node { int i; };
+
+	int * foo()
+	{
+		smart_pointer_to_node p = new node;
+		int * i = &p->i;
+		return i;
+	}
+
+How do we keep the node from being collected now that 
+the smart pointer to it has been destroyed? 
+What's the best course of action here? Forbid taking the
+address of members of a collected object?

Well... essentially... yes.

Actually, "forbid" is not the correct term.  Rather than a total prohibition,
you could simply *encapsulate* the ability to take the address of the
member called `i' within the `struct node' type.

That's quite easy to do.  Just make your data members (e.g. `i') private
to their containing classes.

You ought to be doing that anyway.

-- 

// Ron Guilmette  -  C++ Entomologist
// Internet: rfg@ncd.com      uucp: ...uunet!lupine!rfg
// Motto:  If it sticks, force it.  If it breaks, it needed replacing anyway.