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Date: Sat, 05 Apr 2008 13:36:42 +0200
From: Gautier <gautier@fakeaddress.nil>
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Subject: Re: Ada.Strings.Bounded
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Date: 2008-04-05T13:36:42+02:00
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Pascal Obry wrote:

...
> With Unbounded_String we are close to something "usable".

That's clear. I think Adam's question was really specific to the bounded 
strings. Unbounded_String is the most comfortable and the safest, but needs 
dynamic allocation behind the scenes, which can be a handicap on some special 
situations (performance-critical, systems without dynamic allocation,...).

>    U1 : Unbounded_String;
>    U2 : Unbounded_String;
> 
>    U1 := U2;
> 
> Works fine! But then it becomes a bit messy when converting back and 
> forth with the string type.
> 
>    U1 := To_Unbounded_String ("whatever");
> 
>    Put_Line (To_String (U1));
> 
> Not a big deal, but if we can find a nice way to tell that such routine 
> must be used for conversion between type it will be quite handy.
> 
>    type Unbounded_String is ...;
> 
>    function To_String (U : Unbounded_String) return String;
> 
>    for Unbounded_String'Conversion (String) use To_String;
> 
> Just to get the idea, then one could write:
> 
>    Put_Line (U1);
> 
> Of course this raises some questions:
> 
>    What to do if we have Put_Line defined for String and
>    Unbounded_String? Which version gets called?
> 
> ...
> 
> Anyway that's just some wild thoughts :)

I agree with Dmitry that it would lead to confusing situations, something that 
Ada normally tries to avoid...
What I'm doing to make life easier is to paste the following lines in my sources

   function S (Source : Ada.Strings.Unbounded.Unbounded_String) return String
     renames Ada.Strings.Unbounded.To_String;
   function U (Source : String) return Ada.Strings.Unbounded.Unbounded_String
     renames Ada.Strings.Unbounded.To_Unbounded_String;

After the sources only need short S(...)'s and U(...)'s which are ok to me:

   external_packer: array(External) of Unbounded_String:=
     ( U("zip.exe"),
       U("7z.exe"),
       U("kzip.exe")
     );
...
   return "External: " & S(external_title(a)) & ", " & S(external_options(a));
...
       e.name:= U(unique_name);
..., etc. etc.
______________________________________________________________
Gautier         -- http://www.mysunrise.ch/users/gdm/index.htm
Ada programming -- http://www.mysunrise.ch/users/gdm/gsoft.htm

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