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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Two approaches of iterators for the key-value pairs
Date: Fri, 27 Nov 2015 17:30:17 +0100
Organization: cbb software GmbH
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Date: 2015-11-27T17:30:17+01:00
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On Fri, 27 Nov 2015 07:25:57 -0800 (PST), ytomino wrote:

> Hello, I'm reading AI12-0009-1 "Iterators for Directories and Environment_Variables".
> http://www.ada-auth.org/cgi-bin/cvsweb.cgi/ai12s/ai12-0009-1.txt?rev=1.4
> 
> And there is interesting difference between the new iterator of Ada.Environment_Variables and the existing iterators.
> (The boolean trick of these new iterators is also interesting, but set aside.)
> 
> A loop for Ada.Environment_Variables would be like below, according to this AI:
> 
> for E *of* Ada.Environment_Variables.All_Variables loop
>    -- E is Iterator_Element (Name_Value_Pair_Type)
>    Name (E) -- key
>    Value (E) -- value
> end loop;
> 
> On the other hand, as we already know, a loop for Ada.Containers.Hashed_Maps/Ordered_Maps:
> 
> for I *in* The_Map_Object.Iterate loop
>    -- I is Cursor
>    Key (E) -- key
>    Element (E), Reference (E).Element.all -- value
> end loop;
> 
> If you create new iterator for some key-value pairs, which approach do you like?

Rather this:

for Variable in All_Variables loop
   Put_Line (Variable.Name & "=" & Variable.Value);
end loop;

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de