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From: "Jeffrey R. Carter" <spam.jrcarter.not@acm.nospam.org>
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Subject: Re: Containers - nontrivial element access
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Date: 2007-10-03T18:49:58+00:00
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Dmitry A. Kazakov wrote:
> 
> How so? Ada abstracts by-value/reference issue away (except for some
> special cases). Whether an in-out parameter is passed by reference or by
> value is not a question of sematic in Ada.

I'm not discussing parameter-passing mechanisms.

> This is IMO utterly wrong. The semantics of swapping element's fields is
> well-defined independently on the way of access. In question in not the
> semantics of, but the syntax sugar, namely an array-like indexing of the
> container.

Swapping was only an example. Essentially, the OP was looking for the
ability to do

People.Element (X).Salary := S;

and have it modify the value in the data structure.

C++ uses reference semantics, so that a modification of a field modifies 
the value in the data structure. Ada uses value semantics, so that 
modification of a field does not modify the value in the data structure.

-- 
Jeff Carter
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