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From: rgonzal@elbereth.rutgers.edu (Ralph Gonzalez)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Think C 4.0 evolving to C++
Message-ID: <Feb.26.08.48.18.1991.20826@elbereth.rutgers.edu>
Date: 26 Feb 91 13:48:19 GMT
References: <0.27C5B492@mmug.edgar.mn.org>
Organization: Rutgers Univ., New Brunswick, N.J.
Lines: 56

As mentioned in the Think C manuals, you can get Think C/C++
compatibility as far as "virtual" is concerned by using "virtual" in
all method declarations, and saying:

# ifdef THINK_C
# define virtual
# endif

A few other requirements:

C++ doesn't support Think C's method of avoiding multiple inclusion of
header files.  So you must use the usual C++ approach for all headers:

# ifndef filename_h
# define filename_h

(body of header file)

# endif

"direct" and "indirect" specifiers are not used in C++, so you should
use something like this in your root class:

# ifdef THINK_C
struct Generic_Class:indirect
# else
struct Generic_Class
# endif
{
	virtual boolean init(void);
		.
		.
		.
};

Since "new" and "delete" are implemented as functions in Think C and
operators in C++, you need this in any file using them (or in a common
header):

# ifdef THINK_C
# include <oops.h>
# endif

Since it is not supported in C++, you can't use Think C's "inherited"
keyword.  You should instead use the name of the base class
explicitly.


I've had good luck in Think C/C++ portability by following the above
rules.

There are also a couple of bugs in Think C which you have to work
around, but these don't come up too often...

-Ralph
rgonzal@chowder.rutgers.edu