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From: Stefan Helfert <helfert@galileo.mpi-hd.mpg.de>
Subject: Re: Ada --> C Translation, was: Win CE target
Date: 1998/09/28
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Organization: Max-Plank-Institut fuer Kernphysik Heidelberg
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Newsgroups: comp.lang.ada
Date: 1998-09-28T00:00:00+00:00
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dewarr@my-dejanews.com wrote:
[...]
> Some of the trouble areas in compiling into C are
> 
>   1. Arithmetic overflow checks, especially in complex
>      expressions, which have to be broken down into steps
>      or written in prefix notation.
> 
>   2. Nested procedures, and particularly nested procedures
>      with complex local declarations.
> 
>   3. Subunits (hard to do anything other than create a huge
>      source in which the subunits are substituted).
> 
>   4. Exceptions
> 
[...]
> I will say for the record, that, according to MY definition
> of readability, it is not possible to translate Ada 95 into
> readable C in all cases.

Clearly this is a statement that you cannot argue with.  

But I am tempted to add that the C preprocessor features clearly help to
add readability to a certain degree.  One of my projects some time ago
was a ML2C-translator, where we wanted to preserve "style" (not only
readability).  Now ML covers, as you may know, most of the language
features that Ada sports (especially those mentioned above) and adds
more (famous: garbage collection).  And ML as a functional language is
relying on a different programming paradigm.

The C preprocessor did really help a lot: E.g., you can implement
exceptions with setjmp/longjmp and hide this before the users' eyes, or
hide the interface to the garbage collector/memory management.


Stefan Helfert