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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: implementation of Bounded_String
Date: Thu, 18 Jan 2018 15:42:50 +0100
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Date: 2018-01-18T15:42:50+01:00
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On 18/01/2018 15:10, Mehdi Saada wrote:
> I suppose it's obvious but...
> If I want to reimplement IO of Bounded_String without relying on
> Unbounded_String, can I do without getting reading input one character
> after another ? Has it to do with streams ?

It has to do with whether string bounds is a part of I/O. Stream 
attributes are subdivided into 'Read/'Write and 'Input/'Output. The 
former are without bounds (constraints).

Text I/O is a completely different story because it is related to text. 
You implement Put this way:

    type Bounded_String (Length : Natural := 0) is record
       Current_Length : Natural := 0;
       Data : String (1..Length);
    end record;

    procedure Put (X : Bounded_String) is
    begin
       Put (X.Data (1..X.Current_Length));
    end Put;

There is no reasonable Get to have, but Get_Line could have sense

    procedure Get_Line (X : out Bounded_String) is
    begin
       Get_Line (X.Data, X.Current_Length);
    end Get_Line;

Similarly you can always implement stream attributes decomposed into 
stream operations of other objects.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de