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From: kens@hpldola.HP.COM (Ken Shrum)
Newsgroups: comp.lang.c++
Subject: Re: constructors and instantiation
Message-ID: <11430003@hpldola.HP.COM>
Date: Fri, 16-Oct-87 14:53:13 EDT
Article-I.D.: hpldola.11430003
Posted: Fri Oct 16 14:53:13 1987
Date-Received: Fri, 23-Oct-87 03:24:48 EDT
References: <2575@sigi.Colorado.EDU>
Organization: HP Logic Design Oper. -ColoSpgs
Lines: 30

> I am having difficulty utilizing the Free Store example (8.5.8, pg 280
> of The C++ Programming Language).  ...
> ...
> stamp::stamp (int v) 
        {
                val = v;   //val should not exist since I have not made a call
                           //to new or reserved the space for the object.
                           //obviously it does exist.  Is there an implicit 
                           //call to new? Should I override new with another
                           //function?  How can new be 'intercepted'?   

In <The Book>, pg 280 it states explicitly that you must assign to this
before any use of member if you wish to override the default action.
On pg 164 it is made explicit that any use of a member before such an
assignment is undefined.

Regarding the other problem, you've allocated a stamp on the stack by
writing:

	stamp foo(10);

I believe that assigning a new value to this for objects on the stack
is an undefined operation.  See pg 163, 164.  If you use

	stamp *foo = new stamp(10);

you'll get the behavior you want.

	Ken Shrum
	hplabs!hpldola!kens