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From: "John B. Matthews" <nospam@nospam.invalid>
Newsgroups: comp.lang.ada
Subject: Re: Table of pointers question
Date: Sat, 26 Sep 2009 10:51:04 -0400
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Date: 2009-09-26T10:51:04-04:00
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In article <cj5sb5p5g3jvj6vvdgi56t9m25b6vb93da@4ax.com>,
 Rob Solomon <usenet@drrob1-noreply.com> wrote:
[...]
> The syntax of the statement is also confusing to me.
> 
> EntryPointerList(NumberOfEntries) :=
>             new DirectoryEntryType'(NewEntry);
> 
> It would help me to break this statement down more.  Why is the last 
> part written the way it is?  It uses a single quote and parens.  I 
> don't understand this syntax.  How does this store data on the heap 
> and then return a pointer to assign to the pointer list?

In this context, the allocator [1] includes a qualified expression [2]. 
When the expression is evaluated, "An object of the designated type is 
created and the value of the qualified_expression is converted to the 
designated subtype and assigned to the object." The resulting access 
value, which points to the newly created object, is stored in the 
EntryPointerList array at index NumberOfEntries.

Ada also uses "'" to indicate attributes [3].

[1]<http://www.adaic.com/standards/05rm/html/RM-4-8.html>
[2]<http://www.adaic.com/standards/05rm/html/RM-4-7.html>
[3]<http://www.adaic.com/standards/05rm/html/RM-K.html>

-- 
John B. Matthews
trashgod at gmail dot com
<http://sites.google.com/site/drjohnbmatthews>