From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Generic procedures and their parameters
Date: Wed, 6 Sep 2006 11:43:15 +0200
Date: 2006-09-06T11:43:15+02:00 [thread overview]
Message-ID: <w0vh1ugsvkj1$.2fnx5mt0tplm$.dlg@40tude.net> (raw)
In-Reply-To: edm273$fee$1@sunnews.cern.ch
On Wed, 06 Sep 2006 10:51:48 +0200, Maciej Sobczak wrote:
> eneric
> type Index_Type is (<>);
> type Element_Type is private;
> type Array_Type is array (Index_Type range <>) of Element_Type;
> with function "<" (Left, Right : in Element_Type) return Boolean is <>;
> procedure Sort(To_Sort : in out Array_Type);
>
> My question is: what's the purpose of the third parameter (Array_Type)?
> Isn't it implied by the first two and therefore just redundant?
Reverse. Actually Index_Type and Element_Type are redundant. In a better
Ada it should be:
generic
type Container_Type is array (<>) of <>;
-- or "(<>) is limited private array"
with function "<" (Left, Right : in Container_Type'Element)
return Boolean is <>;
procedure Sort (To_Sort : in out Container_Type);
[ Even better it be non-generic:
procedure Sort (To_Sort : in out Container_Of_Ordered'Class);
where each container type (like an array) be a member of the class, if its
elements are in Ordered'Class. ]
Regarding Array_Type being implied, it is not. You can have any number of
array types based on exactly same combination of index and element types.
These types will be different types:
type I is ...;
type E is ...;
type Array1 is array (I range <>) of E;
type Array2 is array (I range <>) of E;
The types Array1 and Array2 are distinct types. Sort must be instantiated
for each of them (or else you have to convert types).
The reverse is a different story. It is a pity that Ada does not have
attributes to get the index and element types from the array type
(container type). The next step would be getting "<" from the element type,
which would eliminate a need to have Sort generic.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2006-09-06 9:43 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-09-06 8:51 Generic procedures and their parameters Maciej Sobczak
2006-09-06 9:43 ` Dmitry A. Kazakov [this message]
2006-09-06 12:36 ` Maciej Sobczak
2006-09-06 13:11 ` Robert A Duff
2006-09-06 14:14 ` Maciej Sobczak
2006-09-06 15:09 ` Dmitry A. Kazakov
2006-09-06 16:35 ` Georg Bauhaus
2006-09-07 7:32 ` Dmitry A. Kazakov
2006-09-07 6:48 ` Georg Bauhaus
2006-09-07 10:19 ` Dmitry A. Kazakov
2006-09-08 9:11 ` Maciej Sobczak
2006-09-08 10:19 ` Dmitry A. Kazakov
2006-09-09 14:49 ` Robert A Duff
2006-09-09 15:34 ` Dmitry A. Kazakov
2006-09-09 23:26 ` Jeffrey R. Carter
2006-09-10 11:49 ` Robert A Duff
2006-09-10 19:43 ` Jeffrey R. Carter
2006-09-06 13:02 ` Robert A Duff
2006-09-06 14:09 ` Dmitry A. Kazakov
2006-09-08 3:35 ` Randy Brukardt
2006-09-08 7:21 ` Dmitry A. Kazakov
2006-09-09 1:29 ` Randy Brukardt
2006-09-09 7:14 ` Dmitry A. Kazakov
2006-09-09 14:32 ` Robert A Duff
2006-09-06 12:56 ` Robert A Duff
2006-09-07 2:47 ` Steve
2006-09-07 7:47 ` Dmitry A. Kazakov
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