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From: lsr@Apple.COM (Larry Rosenstein)
Newsgroups: comp.sys.mac.programmer
Subject: Re: C++ ... setting new standards for patience
Message-ID: <4801@internal.Apple.COM>
Date: 17 Oct 89 22:35:58 GMT
References: <4208@ncsuvx.ncsu.edu>
Sender: usenet@Apple.COM
Organization: Objects-R-Us,  Apple Computer, Inc.
Lines: 46

In article <4208@ncsuvx.ncsu.edu> jnh@ecemwl.ncsu.edu (Joseph N. Hall) 
writes:

> up into 4 parts to illustrate a kind of one-class-one-file approach to
> OOP.  This means, of course, that all of these header files are processed
> 4 times by cfront ...

One trick that people use is to make a "master" .c file that includes the 
normal .c files (each containing 1 class).  In the cases where you know 
that you are going to compile a 4 classes, you are better off compiling 
the master .c file and parsing the headers only once.

> Naturally, there is no #pragma load for cfront.  Not only do you have to
> include _more_ headers with cfront, you can't pre-compile them, and they
> are processed more slowly by cfront than by c, THEN they have to be
> processed by C, and they STILL can't be pre-compiled.  

The headers are only processed by CFront.  The output of CFront is C code 
with all the headers & macros expanded.

#pragma dump/load is high on the list of enhancements for CFront.  As you 
said, it isn't a trivial addition.  I don't know if this will be in C+ 3.1 
final.  (As a C++ user, I hope so.)

> Cfront and C include special "gibberish" switches (-z3) that produce
> and read (respectively) special non-TEXT output; these aren't documented 

This is a performance improvement.  CFront outputs a token stream which is 
directly read by the C compiler.  This avoid having to re-parse the output 
from CFront.  You can ask to see the generated C code with the -c option 
to CPlus.

> are used in the CPlus script.  The result, when there's an error that 
isn't
> caught by cfront but which is caught by C, is something like:

Any error that is reported by the C compiler is a bug in CFront, no 
question about it.  CFront is supposed to catch all the program syntax 
errors, so you should never see errors reported by the C compiler. 


Larry Rosenstein, Apple Computer, Inc.
Object Specialist

Internet: lsr@Apple.com   UUCP: {nsc, sun}!apple!lsr
AppleLink: Rosenstein1