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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: overload ":=" ???
Date: 1996/07/25
Message-ID: <Dv45E5.MHJ@world.std.com>#1/1
X-Deja-AN: 170530613
references: <31ED3F5F.1135B4EA@jinx.sckans.edu> <dewar.837646128@schonberg>
 <4t7l2p$n41@zdi.informatik.uni-stuttgart.de>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: comp.lang.ada
Date: 1996-07-25T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <4t7l2p$n41@zdi.informatik.uni-stuttgart.de>,
Wolfgang Gellerich <gelleric@kafka.informatik.uni-stuttgart.de> wrote:
>What is the problem with overloading := ?

Unconstrained discriminated records.  This problem is explained in
AARM-7.6(17.a - 17.h).

>... In the case discussed here, assigning
>a string literal to an unbounded strng variable, there should be no 
>difficulties ?

This case discussed here, actually, would be better addressed by having
user-defined literals, rather than user-defined assignment.  Or, it
could be addressed by having user-defined implicit conversion, but that
seems like overkill.  Consider that you might want:

    procedure P(X: Fancy_Dynamic_String);
    ...
    P("Hello, world.");

whereas Ada requires:

    P(To_Fancy_Dynamic_String("Hello, world."));

or:

    P(+("Hello, world."));

Assuming, that is, that you buy the premise of the original poster, who
said that `X := To_Fancy_Dynamic_String("Hello, world.");' is too
verbose.

- Bob