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From: Paul Rubin <no.email@nospam.invalid>
Newsgroups: comp.lang.ada
Subject: Re: How to get Ada to ?cross the chasm??
Date: Mon, 07 May 2018 22:46:41 -0700
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Date: 2018-05-07T22:46:41-07:00
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gautier_niouzes@hotmail.com writes:
> https://unzip-ada.sourceforge.io/ )

I downloaded this and found:

1) the file fizzip.adb didn't compile because it used 'Image in an
improper way in a bunch of places.  I found on Stack Overflow that
there's a GNAT attribute 'Img that got it to work.

2) gprbuild made a zipada program but no unzipada.  Unzip is commented
out of the .prj file.

3) The bunzip program it builds is around 25% slower than the default
Linux one, which is reasonable if it's safer, i.e. specifically if it's
free of potentially unsafe memory accesses.  I heard somewhere that
optimized GNAT turns off subscript checking by default, which seems
un-Ada-like.  But, from C++ stdlib containers, I think subscript checks
are cheaper than most people might expect.

4) The lzma_enc program it builds runs noticeably faster than 
xz --format=lzma, but it also doesn't compress as well, so I suspect the
algorithms are similar but the parameters are different.   I don't
see a way to set the compression level in the Ada version.  I might
experiment with xz's settings to find one that matches lzma_enc.

I'm very glad that someone implemented those programs in Ada since there
have historically been various bugs in the C versions that allowed code
injection exploits etc.

Regarding crossing the chasm, it would sure be nice if Ada (at least
GNAT) were more interoperable with C and C++ on Linux, in the sense of
using the same makefiles and similar command line tools.  Ada seems to
want to be in its own world of Gprbuild and .prj files.