Path: utzoo!attcan!uunet!taumet!mike
From: mike@taumet.com (Michael S. Ball)
Newsgroups: comp.lang.c++
Subject: Re: operator++()   and   testing 'this'
Message-ID: <479@taumet.com>
Date: 16 Oct 90 16:16:31 GMT
References: <1990Oct14.224706.1934@nowhere.uucp> <58242@microsoft.UUCP>
Reply-To: mike@taumet.UUCP (Michael S. Ball)
Organization: Taumetric Corporation, San Diego
Lines: 18

In article <58242@microsoft.UUCP> jimad@microsoft.UUCP (Jim ADCOCK) writes:

>Good point.  Embedded objects are another good example why C++ compilers 
>DO NOT typically support the (this==0) test to see if objects are on the
>heap or not.  I haven't seen a C++ compiler released in years that 
>supports this test.  Correct me if you find a counter-example.  The reason

Try all cfront versions, Oregon C++, Turbo C++, Zortech (at least earlier
versions).  It's absolutely necessary if assignment to this is allowed.

What has probably misled you is that it only works if you DO assign to
this within the constructor.  If you don't the compiler generates code
to check for a zero value and allocate space for you, thus making the
value non-zero by the time you get to the user code.

Mike Ball
TauMetric Corporation
mike@taumet.com