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Re: GNUstep on Darwin


From: Helge Hess
Subject: Re: GNUstep on Darwin
Date: Wed, 04 Apr 2001 23:43:50 +0200

address@hidden wrote:
> >You expect that if you combine Darwin and GNUstep you will be able to
> >run MacOSX *binaries* ??? Of course this is basically impossible for
> >various reasons.
> >GNUstep provides *source code* compatibility at best.
> 
> I thought it just might work because the processor is the same, the
> executional format (binary) is the same (same basic OS) and the
> libraries aim to do the same. Are some dataformats different?

It definitly won't work !

The only common thing between MacOSX and GS is the API and some ASCII
data formats (eg plists). At binary level they are completly
incompatible ! That the external dataformats (eg object archives, NIB
files) are different is the smallest problem.

The most obvious way to show this is the fragile base class and ivar
layout problem. Almost any MacOSX program will subclass some of the
Foundation classes. But the Apple Foundation classes have entirely
different memory layouts and even different instances sizes than GS
Foundation classes.

Apple Foundation and GS Foundation are somewhat similiar to Linux/PPC
and Linux/ix86. You can usually compile the same (C) source code on
Linux/PPC and Linux/ix86 without any sourcecode change since the API
(system calls, system libs) are exactly the same, but you can't just
exchange binaries. The same is true with the two (and the other)
Foundation libs. The API is the same, but the internal binary structure
is completly different.

Greetings
  Helge
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