From: Bob Duff <bobduff@theworld.com>
Subject: Re: Bounded String question
Date: Wed, 11 Nov 2015 10:41:34 -0500
Date: 2015-11-11T10:41:34-05:00 [thread overview]
Message-ID: <87a8qk7dch.fsf@theworld.com> (raw)
In-Reply-To: 66278720-249a-4191-a908-bb840e7f3ccc@googlegroups.com
Serge Robyns <serge.robyns@gmail.com> writes:
> Hi Bob,
>
> On Wednesday, 11 November 2015 01:48:43 UTC+1, Bob Duff wrote:
>> How about:
>>
>> function No_Client_Name return T_Client_Name is
>> (T_Client_Name (P_Strings.Null_Bounded_String));
>
> May idea was to have a "constant" and use language construct/semantic to expose
> that. I was expecting that the compiler will have more optimization options
> with such a construct than a dynamic construct like above.
I doubt that. Especially if you put Inline.
>> But why do you need Preelaborate? It's not all that much use if you use
>> GNAT's static elaboration model.
>
> Just for the sake of "cleanness" and again using language features to express
> my intent as per my "expectations". Even if I would end up using GNAT in all
> cases.
One possibility is to use the option in GNAT that tells you where to put
pragma Elaborate_All, and put them in by hand. Then you don't need
Preelaborate.
>> > Maybe I'm using bounded strings completely wrong.
>>
>> Well, I think the Ada.Strings.Bounded package is way overengineered.
>> So "using Ada.Strings.Bounded" = "using bounded strings wrong". ;-)
>> I suggest rolling your own. No need for generics.
>>
>> type Bounded_String (Max_Length : Natural := ...) is limited record
>> Length : Natural := 0;
>> Chars : String (1 .. Max_Length);
>> end record;
>>
>> along with a few trivial operations.
>
> I tend to agree that the bounded strings seems over-engineered but I'm lacking
> Ada experience to judge that properly. However it is indeed a pain to use
> compared to other languages where I come from, e.g. C. I don't know why
> strings are so complex to use in Ada. At various places I've conversions
> between bounded strings and plain strings in order to offer a consistent API to
> my modules. Luckily the package already provide a To_String function. However,
> I've had to write loads of functions like "To_Client_Name (Name : in String)
> return T_Client_Name is (T_Client_Name (P_Strings.To_Bounded_String (Name));"
> as I haven't found a more direct way to convert a string to the type.
Can't you call the inherited To_Bounded_String directly?
>...This with
> some other oddities in Ada is what do give me a lot of frustrations. However,
> I do remain decided to proceed with Ada, as I do believe in its core principles
> of allowing developing reliable software.
>
> Now with regards to rolling my own, is this not defeating re-use? Why shall I
> waste my time on such a feature while I'm having loads of things to do on the
> application itself.
I'm all for reuse. But in this case, the thing you're reusing causes a
fair amount of trouble, and rolling your own using the type I showed
above is trivial.
> I've been considering using unbounded strings instead but then I'm dropping the
> idea of a bounded storage for my entities. Most of these "strings" ends up in
> record types which in the end will map to database entities.
Right, if you don't have a known bound, and you're not developing for a
small embedded system, then unbounded strings are often appropriate.
Those are complicated enough that I would not recommend rolling your
own.
Another alternative is Ada.Containers.Vectors instantiated with
Character.
- Bob
prev parent reply other threads:[~2015-11-11 15:41 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-10 22:00 Bounded String question Serge Robyns
2015-11-11 0:48 ` Bob Duff
2015-11-11 2:01 ` Jeffrey R. Carter
2015-11-11 15:34 ` Bob Duff
2015-11-11 17:36 ` Jeffrey R. Carter
2015-11-11 19:22 ` Bob Duff
2016-03-06 18:59 ` Xavier Petit
2016-03-07 23:16 ` Randy Brukardt
2016-03-08 0:08 ` Jeffrey R. Carter
2016-03-09 1:18 ` Randy Brukardt
2015-11-11 10:52 ` Serge Robyns
2015-11-11 13:43 ` Serge Robyns
2015-11-11 14:32 ` brbarkstrom
2015-11-11 16:08 ` Serge Robyns
2015-11-11 17:27 ` Jeffrey R. Carter
2015-11-11 20:06 ` Serge Robyns
2015-11-11 20:23 ` AdaMagica
2015-11-11 20:27 ` AdaMagica
2015-11-11 20:32 ` Serge Robyns
2015-11-11 20:40 ` AdaMagica
2015-11-12 17:31 ` Serge Robyns
2015-11-12 19:10 ` AdaMagica
2015-11-12 21:29 ` Randy Brukardt
2015-11-12 18:03 ` G.B.
2015-11-12 18:13 ` Serge Robyns
2015-11-12 18:14 ` Serge Robyns
2015-11-12 19:37 ` Randy Brukardt
2015-11-11 20:42 ` Jeffrey R. Carter
2015-11-12 16:59 ` Serge Robyns
2015-11-12 18:39 ` Jeffrey R. Carter
2015-11-12 21:19 ` Randy Brukardt
2015-11-12 21:27 ` Randy Brukardt
2015-11-12 22:32 ` Jeffrey R. Carter
2015-11-13 0:07 ` Randy Brukardt
2015-11-13 1:01 ` Jeffrey R. Carter
2015-11-11 15:41 ` Bob Duff [this message]
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