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From: dmmg1176@uxa.cso.uiuc.edu (David M Marcovitz)
Newsgroups: comp.sys.mac.programmer
Subject: Think C #include Question
Message-ID: <1991Feb28.223430.24645@ux1.cso.uiuc.edu>
Date: 28 Feb 91 22:34:30 GMT
Sender: usenet@ux1.cso.uiuc.edu (News)
Organization: University of Illinois at Urbana
Lines: 43


I am working with 3 classes (call them Foo, Bar, and Baz).  Foo and
Bar are subclasses of Baz.  There header files are as follows:

-----------Foo.h-----------
#define _H_Foo   /* prevents file from being included more than once */

#include Baz.h  /* superclass header */
#include Bar.h  /* other file's header */

struct Foo : Baz
{
    Bar *myBar; /* an object of the Bar class */
       .
       .
};

----------Bar.h------------
#define _H_Bar

#include Baz.h
#include Foo.h

struct Bar : Baz
{
    Foo *myFoo; /* an object of the Foo class */
       .
       .
};
---------------------------

The problem is that I want each Foo to know about a Bar, and I want
each Bar to know about a Foo.  Unfortunately I get a syntax error when
I try to compile.  When compiling Bar.h, it first has to compile
Foo.h.  When Foo.h tries to declare myBar, it can't because the Bar
class has not been; thus I get a syntax error.

How can I get around this problem?

--
David M. Marcovitz                     |  internet: marcovitz@uiuc.edu
Computer-based Education Research Lab  |            dmmg1176@uxa.cso.uiuc.edu
University of Illinois                 |  novanet:  marco / cca / cerl