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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Practicalities of Ada for app development
Date: Sun, 10 Jun 2012 21:47:37 +0200
Organization: cbb software GmbH
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Date: 2012-06-10T21:47:37+02:00
List-Id: <comp.lang.ada>

On Sun, 10 Jun 2012 19:04:02 +0200, Yannick Duch�ne (Hibou57) wrote:

> Le Sun, 10 Jun 2012 17:49:40 +0200, Shark8 <onewingedshark@gmail.com> a  
> �crit:
>> Ironically, most of them aren't used in the mainstream of software  
>> development which tends to fall back on C's string manipulation [style  
>> of] functions or Regex (which is horrible if you look at Regex from a  
>> maintenance perspective.).
> 
> If Regular Expressions appears as is, as literals in the program, yes,  
> that's a maintenance nightmare. But you may decompose the expressions,  
> build them incrementally (I use to do it with Python), or even fork to  
> something similar which could use objects and structures instead of  
> unreadable literal expressions (I don't one, just an idea).

That does not change the fact that SNOBOL patterns are far more powerful
(the language generated is of a much wider class), much more readable. The
problems are that any patterns are unmaintainable unless trivial. Trivial
patterns require no special means. Another problem is not in having pattern
as an object. This is well possible in Ada. The actual problem is to have a
pattern matching construct in the language. You need something like

   match Variable in Stream by Pattern do
       ...
   end match;

which would initialize Variable or set of variables by matched parts of the
Pattern while advancing Stream while the pattern is matched. It is very
difficult to describe in a structured manner. The way SNOBOL handles that
is total mess. Variables are specified in the pattern. Success and failure
are just labels etc. It is not worth the efforts to bother about that,
because, as I said, patterns is a bad idea in general.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de