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Date: Wed, 30 Apr 2008 11:21:06 +0200
From: Georg Bauhaus <rm.tsoh.plus-bug.bauhaus@maps.futureapps.de>
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Subject: Re: Access keyword
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Date: 2008-04-30T11:21:06+02:00
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Maciej Sobczak wrote:
> On 29 Kwi, 23:32, "Randy Brukardt" <ra...@rrsoftware.com> wrote:
> 
>> Anonymous access types (a superset of access parameters) mainly exist in Ada
>> to make it easier for C++ and Java programmers to move their rotten designs
>> to Ada.
> 
> Anonymous access types are used by Ada.Containers for iteration (among
> others). "Rationale" by Barnes presents some nice examples with
> downward closures as well.

Aren't these implementation types (needed in the body of an
Integrate procedure, say) rather than types exposed by some
public signature?

Similarly, the Process procedures, passed as access parameters
to Iterate in Ada.Containers, enable referring to parameters of
some surrounding subprogram (the downwards closures you mention
had not been in the original Charles-derived design, which had
started from generics (that cannot refer to parameters)).
So again, these access parameters are good for implementing
things. However, they need not be shown to public clients of
things.