From: "J-P. Rosen" <rosen@adalog.fr>
Subject: Re: Inferring array index type from array object
Date: Wed, 23 Jun 2010 11:03:17 +0200
Date: 2010-06-23T11:03:17+02:00 [thread overview]
Message-ID: <hvsikv$3a7$1@news.eternal-september.org> (raw)
In-Reply-To: <1305oqccr1h2t$.x33x4oxwd84d$.dlg@40tude.net>
Dmitry A. Kazakov a �crit :
>> I would like to declare I as a free variable instead and I would
>> expect some symmetry in the language by doing this:
>>
>> I : S'Range := S'First;
>
> subtype Index_Span is Integer range S'Range;
> I : Index_Span := S'First;
Or simply:
I : Positive range S'Range;
>> 1. What is the standard justification for this assymetry?
This is a simplification of loops, to avoid some typing to the user.
Think of it the other way round: since a for loop involves the
declaration of an object, the type should always be explicitely declared
(a coding rule that I apply - of course checkable by AdaControl):
for I in positive range 1..10 loop ...
for I in positive range S'Range loop ...
So it is really symetrical, except that in the case of a loop, you are
allowed to "simplify" by omitting the "<type> range" part - forcing the
compiler to deduce the type from the range, which is not a good idea IMHO.
>> 2. Is it possible to declare the index variable without hardcoding the
>> index type (that is, to infer it from the array object)?
>
There is no point in doing this, since the type of the array /is/
hardcoded anyway. You could allow the same "simplification" as for
loops, but as mentionned above, I prefer the other way round: always
explicitely give the type name.
--
---------------------------------------------------------
J-P. Rosen (rosen@adalog.fr)
Visit Adalog's web site at http://www.adalog.fr
next prev parent reply other threads:[~2010-06-23 9:03 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-23 7:30 Inferring array index type from array object Maciej Sobczak
2010-06-23 8:01 ` Dmitry A. Kazakov
2010-06-23 9:03 ` J-P. Rosen [this message]
2010-06-23 12:24 ` Georg Bauhaus
2010-06-23 12:52 ` J-P. Rosen
2010-06-23 19:09 ` Simon Wright
2010-06-24 7:25 ` Georg Bauhaus
2010-06-23 14:38 ` Robert A Duff
2010-06-23 15:17 ` J-P. Rosen
2010-06-23 17:17 ` Robert A Duff
2010-06-24 6:16 ` J-P. Rosen
2010-06-23 12:13 ` Niklas Holsti
2010-06-23 14:27 ` Peter C. Chapin
2010-06-23 20:24 ` Niklas Holsti
2010-06-23 16:33 ` Warren
2010-06-23 17:49 ` Dmitry A. Kazakov
2010-06-23 18:45 ` Warren
2010-06-23 20:39 ` Niklas Holsti
2010-06-28 13:44 ` Warren
2010-06-28 22:18 ` Niklas Holsti
2010-06-29 1:49 ` Adam Beneschan
2010-06-29 2:10 ` (see below)
2010-06-29 16:56 ` Warren
2010-06-29 17:50 ` John B. Matthews
2010-06-29 19:31 ` Warren
2010-06-29 20:06 ` Jeffrey R. Carter
2010-06-29 20:16 ` Warren
2010-06-29 20:22 ` Adam Beneschan
2010-06-29 20:39 ` Dmitry A. Kazakov
2010-06-29 20:55 ` Warren
2010-06-29 21:00 ` Warren
2010-06-29 21:47 ` John B. Matthews
2010-06-29 21:52 ` Damien Carbonne
2010-06-29 22:22 ` Adam Beneschan
2010-06-30 16:43 ` Warren
2010-06-29 21:18 ` Jeffrey R. Carter
2010-06-30 5:01 ` Simon Wright
2010-06-30 14:29 ` Adam Beneschan
2010-06-29 20:28 ` Damien Carbonne
2010-06-29 21:20 ` John B. Matthews
2010-06-23 13:12 ` Gautier write-only
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