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From: "Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>
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Subject: Re: Proposal: Auto-allocation of Indefinite Objects
Date: Mon, 27 Jul 2020 22:31:34 +0200
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On 7/27/20 7:48 PM, Brian Drummond wrote:
> 
> Is there any way we could generalise the (storage, access and lifetime
> aspects of) Unbounded_String for unconstrained arrays and discriminated
> records in such a way that Unbounded_String can be a simple instantiation
> of one of these?

Ada.Strings.Unbounded can be considered a combination of 
Ada.Containers.Indefinite_Holders instantiated for String and 
Ada.Containers.Vectors instantiated with Positive and Character, with some 
additional operations added.

The To_String and To_Unbounded_String operations of Unbounded_String are similar 
to the Element and Replace_Element operations of Holder, which do not exist for 
Vector.

The indexed operations of Unbounded_String are similar to the indexed operations 
of Vector, which do not exist for Holder.

If Ada.Containers.Vectors had an additional generic formal type

    type Fixed is array (Index_Type range <>) of Element_Type;

and 2 new operations

    function To_Fixed (From : Vector) return Fixed;
    function To_Vector (From : Fixed) return Vector;

then we wouldn't need Ada.Strings.Unbounded.

-- 
Jeff Carter
"Blessed is just about anyone with a vested interest in the status quo."
Monty Python's Life of Brian
73