Re: Ada & MacOS

["Jeffrey R. Carter" <spam@spam.com>]

Maciej Sobczak wrote:

> Same for C++. One of the users of my recent code (non-trivial, I would 
> say) compiled it on MacOS by typing "make", even though I've never 
> touched Mac. So?

Using which compilers and what language features? Very few "C++" compilers 
implement the language defined by the ISO standard. Can you use all the features 
of the standard language and count on it compiling with all "C++" compilers?

With Ada, the entire standard language is compiled by every compiler; a compiler 
that didn't implement, say, generics, would be laughed out of existence. Yet 
"C++" users regularly use compilers that don't implement templates, exceptions, 
or namespaces.

Sure, Ada compilers are large programs and have errors. They're less common than 
back in the good old days when it seems I broke a compiler every time I turned 
around.

Ada compilers can implement compiler-dependent pragmas and attributes, and can 
supply compiler-dependent packages. Many also supply platform-dependent 
packages. If you use those, you're not writing portable code. If you stick to 
the standard language, though, portability is pretty much guaranteed.

GNAT is an interesting beast. Versions exist for a number of platforms, and it 
comes with a large library (GNAT.*) that is compiler dependent, and much of it 
(such as GNAT.OS_Lib) seems platform dependent, too. These work fine on all 
platforms that GNAT compiles to. So you have compiler-dependent but 
platform-independent packages with GNAT.

-- 
Jeff Carter
"Ada has made you lazy and careless. You can write programs in C that
are just as safe by the simple application of super-human diligence."
E. Robert Tisdale
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