From: stt@henning.camb.inmet.com (Tucker Taft)
Subject: Re: type is access cf type is access all?
Date: Tue, 24 Jan 1995 18:36:48 GMT
Date: 1995-01-24T18:36:48+00:00 [thread overview]
Message-ID: <D2xADD.C5M@inmet.camb.inmet.com> (raw)
In-Reply-To: 1995Jan20.114005.8916@vax.sbu.ac.uk
In article <1995Jan20.114005.8916@vax.sbu.ac.uk>,
<fintan@vax.sbu.ac.uk> wrote:
>trying to get my head around this one and failing!
>(Maybe I need a new head?)
>
>What is the difference between:
>
> type FooPointers is access Foo;
>
>and
>
> type FooPointers is access all Foo;
>
>The 9X LRM states
>
>"if no general_access_modifier {all | constant} appears
>... the access type is a pool-specific access-to_variable
>type"
>
>My reading of this implies that omitting all will result
>in variables the access type only being able to designate
>dynamically (new) allocated anonymous variables and not
>non-pool (aliased) variables.
You are exactly right.
>A check of this idea on gnat 2.0 suggests that both types
>can designate dynamic and aliased variables.
>
>Anyone know the answer?
GNAT is not yet fully conformant with Ada 95. It should
complain if you try to use 'Access to generate a value
of a "pool-specific" access type.
Pool-specific access values may only designate
objects created by allocators. This allows pool-specific
access values to have a representation unique to
their type, such as an index or offset into the access
type's storage pool, rather than a full machine address.
Access values of a "general" access type will generally
be full machine addresses, since they can designate objects
"anywhere."
>Fintan Culwin PhD
>South Bank University
>London SE1 0AA
>
>fintan@vax.sbu.ac.uk
-Tucker Taft stt@inmet.com
Intermetrics, Inc.
next prev parent reply other threads:[~1995-01-24 18:36 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
1995-01-20 11:40 type is access cf type is access all? fintan
1995-01-24 14:32 ` Robert Dewar
1995-01-24 15:55 ` Michael Feldman
1995-01-24 18:36 ` Tucker Taft [this message]
1995-01-25 21:27 ` Robert Dewar
replies disabled
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox