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Newsgroups: comp.lang.ada
Date: Mon, 7 May 2018 00:02:34 -0700 (PDT)
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Subject: Re: Trait based containers
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Xref: reader02.eternal-september.org comp.lang.ada:52062
Date: 2018-05-07T00:02:34-07:00
List-Id: <comp.lang.ada>

> I'm not sure either, but I hope they revert the changes to Map iterators
> if they do add it to Ada202x.  I'm not sure why they changed it to iterate
> over the keys instead as that seems like the least useful way to iterate
> over a map, and you could still access keys via the cursor.  Now the less
> useful way is the default.

One of the main principle in the design of that library is that people could
change most of the details. For instance, if you do not like the default
iterator that returns a key, you can easily derive your own that returns an
element instead.

Initially, I had wanted to return a tuple (key, element) directly. This is really
what a cursor is. So instead of doing

    for A of Map loop

you do

   for C in Map.Iterate loop

and you get both key and element.

I prefer to return a key in the "for..of" loop case, because with a map you
can always go from key->element. The opposite might not  be true.