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From: Matthew Heaney <matthew_heaney@acm.org>
Subject: Re: should I be interested in ada?
Date: 1999/02/19
Message-ID: <m3k8xf3zkl.fsf@mheaney.ni.net>#1/1
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NNTP-Posting-Date: Thu, 18 Feb 1999 18:16:30 PDT
Newsgroups: comp.lang.ada
Date: 1999-02-19T00:00:00+00:00
List-Id: <comp.lang.ada>

fraser@nospam.com writes:

> In fact, one of my favourite things about Ada is the various ways in
> which you can specify a range.  I generally pick the lowest one on the
> following list that's available in the context:
> 
>    for I in 1 .. 10 loop
>    for I in Low .. High loop

Perhaps I'm being pedantic, but I don't recommend these forms.  It's
better to try to assert the type somehow.  I sometimes see this:

    for I in 1 .. 10 loop

        ... Array_Object (I) ...

    end loop;

but this makes me cringe.  Yes, I know the type of index I "defaults" to
Integer, but I'd rather you state that fact explicitly:

    for I in Positive range 1 .. 10 loop


If you use this technique, you avoid the esoterica like

    for I in -1 .. 10 loop

that wouldn't compile in Ada83.  Just do this instead:

   for I in Integer range -1 .. 10 loop

and all is well, no matter which version of the language you're using.

The only time I like to use the form

   for I in 1 .. 10 loop

is when I need to do some work that number of times, and I'm not
actually using index in the body of the loop.  Maybe a better choice of
loop index name is

   for Count in 1 .. 10 loop

to emphasize that this is not an array index.



>    for I in Discrete_Type loop
>    for I in Array_Type'Range loop
>    for I in Array_Object'Range loop

I like these better.

> (I think I read this in the Quality and Style Guide).

Well, yet another guideline in that book I disagree with.