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From: "Nick Roberts" <nickroberts@adaos.worldonline.co.uk>
Newsgroups: comp.lang.ada
Subject: Re: List container strawman 1.1
Date: Thu, 15 Nov 2001 03:49:11 -0000
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Date: 2001-11-15T03:49:11+00:00
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"Jeffrey Carter" <jeffrey.carter@boeing.com> wrote in message
news:3BF2F0E7.5DD40B4B@boeing.com...
> Ted Dennison wrote:
> > The problem with that is that it won't work in an initialization.
>
> Since a list will initialize itself to empty, I don't see that as a
> problem. We may be willing to allow people to use lists in a functional
> manner, with all the implicit deallocation and allocation for deep
> copies that implies for a dynamic structure, but we certainly don't want
> to encourage it.

I think there will sometimes be situations where it would be pretty
inconvenient not to be able to build a singleton list value 'on the fly'.
Suppose we wanted to use someone's wonderful utility procedure Send_Mail to
send an e-mail Father Christmas. We might want to make a call such as:

   procedure Send_Mail (Recipient   => Single("santa@north.pole"),
                        CC          => To_List(("taxman@inland.rev",

"thewishfairy@nevernever.land"));
                        Text        => "Dear Santa, please could I have
...",
                        Attachments => Single(List_of_Presents));

This call has three lists made up inline. Imagine havine to declare two or
three list variables instead, and then call a procedure for each to give it
the right value. Not really a problem, but a lot less convenient.

--
Best wishes,
Nick Roberts