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From: chuq@sun.uucp (Chuq Von Rospach)
Newsgroups: net.micro.mac
Subject: Re: binary postings (Re: net.sources.mac and shareware (...))
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Date: Wed, 20-Nov-85 12:42:31 EST
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Posted: Wed Nov 20 12:42:31 1985
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> 	a) a list of differences between various compilers
> 	b) guidelines for writing "portable" Mac programs
> 	c) automatic conversion programs for certain compiler pairs

Well, there are three potential problems you run into, just looking at the
C compilers:

    o incompatible libraries - the different C compilers have implemented 
	the Toolbox interfaces using different capitalization schemes,
	so GetNextEvent() in Mac C may be getnextevent() in megamax. I
	think that they are slowly working towards fixing this, but some of
	the compiler writers evidently couldn't help "improving" on Inside Mac.

    o incompatible assemblers - different compilers support different forms
	of inline assembler, or don't support them at all. They have also
	developed their own object formats rather than standardizing on
	Apple's MDS format.

    o incompatible toolbox interfaces - This is the kicker. Some systems
	try to bury their toolbox interfaces, either by doing string
	conversions and other things within the library or using a special
	function calling (Sumacc hides the Toolbox incompatibilities as
	much as possible, Megamax uses a special pascal function definition
	type). Others (Mac C, for example) simply lets the programmer
	figure out how to do the interface with a small glue routine. 

At one point I was porting example from Sumacc to Mac C. The only place I
had any problem at all was where Sumacc and Mac C had different ideas of
talking to the Toolbox. Mac C lets the programmer do it, Sumacc tries to
help, and occasionally gets in the way because of it. I finally stopped due
to lack of time (I may finish it Real Soon Now) but not until I came to the
realization that these differences were enough that I couldn't just use an
ifdef to define between the compilers, and Sumacc and Mac C are quite close
to each other. I'm currently looking at rewriting SKEL into Mac C, but
it'll be from scratch instead of a port because there are major differences
in the details of the code. I don't see how that can be automated, offhand.

> 	d) [this is working in a very different direction]
> 	   the definite compiler review showing that we should all use
> 	   brand X

For C compilers, I like Mac C. Why? It was one of the first on the market.
It reads MDS assembler, meaning that you can use anything shipped out of
apple. It reads MDS object files, meaning you can use any of the Apple
supplied libraries (like MacinTalk). Version 4.0 has a new optimizing
linker that gets rid of dead code, meaning smaller applications. It also no
longer needs MDS, so you don't have to buy anything else to make it run,
so the cost isn't outrageous now. The Mac C people have also tried to not
improve on the Inside Mac definitions so you don't have to do as much
translation from the documentation to reality. There is also now a book out
called "Using the Macintosh Toolbox with C" by three guys from Berkeley
that is wonderful (review pending -- I just got it, but a mini-review is
"BUY IT. NOW.")

My second choice would be Sumacc, but everyone doesn't have access to a
good cross development environment. I've looked at a fair amount of Megamax
code, and I don't happen to like it because they've taken a lot of
liberties with toolbox names that give me headaches trying to convert back
and forth.

-- 
:From catacombs of Castle Tarot:        Chuq Von Rospach 
sun!chuq@decwrl.DEC.COM                 {hplabs,ihnp4,nsc,pyramid}!sun!chuq

Let us now take the sacre oath. As of now, he is no longer an elephant!