Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!usc!cs.utexas.edu!uunet!ncrlnk!ncratl!scotty!dspoon
From: dspoon@scotty.Atlanta.NCR.COM (Dave Witherspoon)
Newsgroups: comp.lang.c++
Subject: Re: A solution to the multiple inclusion problem
Message-ID: <1036@scotty.Atlanta.NCR.COM>
Date: 31 Oct 89 19:47:41 GMT
References: <14240@well.UUCP> <1989Oct23.191634.6345@cs.rochester.edu> <1144@odin.SGI.COM>
Distribution: comp
Organization: NCR Corporation, E&M Atlanta
Lines: 25

In article <1144@odin.SGI.COM>, shap@delrey.sgi.com (Jonathan Shapiro) writes:
> In article <1030@ncratl2.Atlanta.NCR.COM> dspoon@ncratl2.Atlanta.NCR.COM (Dave Witherspoon) writes:
> >
> >Say I have 2 classes, A and B.  A contains a B*, and B contains an A*.
> >Thus, we have a circular dependency!  One proposal (that I've tried):
> >
> 
> The following should do what you want.  The trick is to recognize that
> you don't really have a circular dependency at all:
> 
> All C++ needs to know is that A/B are classes to construct a pointer
> to them.  It doesn't need to know what the contents are until you go
> to use them.

If instead my A class contains a B, then the compiler MUST know the full
size of B.  Or if my A class has an inline function that invokes some B
method, then the compiler must see B's class declaration.  I believe in
either of these cases, then it is truly a circular dependency.  In fact,
we even have dependency "triplets".

Other "wrapper" type methods I tried did not solve this problem.
-------------------------------David Witherspoon-------------------------------
D.Witherspoon@Atlanta.NCR.COM         | "Dolphins find humans amusing, but 
NCR Retail Systems Development/Atlanta|  they don't want to talk to them."
MY OPINIONS...ALL MINE!!!             |               - David Byrne