From: Robert A Duff <bobduff@shell01.TheWorld.com>
Subject: Re: Limited_Controlled and out parameters
Date: Fri, 22 Jun 2012 17:41:22 -0400
Date: 2012-06-22T17:41:22-04:00 [thread overview]
Message-ID: <wccy5nff2il.fsf@shell01.TheWorld.com> (raw)
In-Reply-To: af8dd3f8-fa22-4485-ae8e-8a21f3210bbd@googlegroups.com
Adam Beneschan <adam@irvine.com> writes:
> Can a controlled variable (or subcomponent) ever really be
> uninitialized?
In Ada, the concept of "uninitialized" applies only to scalars.
Access types are initialized by default. And composite types
have no such notion -- you can only talk about whether none, some,
or all of their scalar subcomponents are initialized.
> I guess it might, or it might be partly uninitialized. However, if the
> controlled type has a Finalize routine that reads components of the
> type, those components had darn well better not be uninitialized
> garbage.
Right, if scalar.
>...(That is, allowing for cases where, say, a Boolean component
> indicates whether other components in the record are initialized or not.
> But that Boolean had better not be garbage.)
Right. You can give that Boolean a default. Or you can make
sure default initialization never happens, for example, by using
unknown discriminants -- "(<>)".
- Bob
next prev parent reply other threads:[~2012-06-22 21:41 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-22 13:37 Limited_Controlled and out parameters Maciej Sobczak
2012-06-22 15:43 ` Adam Beneschan
2012-06-22 16:58 ` J-P. Rosen
2012-06-22 19:12 ` Adam Beneschan
2012-06-22 21:41 ` Robert A Duff [this message]
2012-06-22 20:22 ` Randy Brukardt
2012-06-23 12:02 ` Maciej Sobczak
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