From: Yossef Mendelssohn <ymendel@...>
Date: 2009-03-05T01:44:39+09:00
Subject: Re: Any solutions to Ruby's inconsistencies?

On Mar 4, 10:02 am, "C. Dagnon" <c-soc-rubyfo...@dagnon.net> wrote:
> 3. Originally I was taught that symbols were the salvation of memory and
> key problems - and they certainly sounded like it.  Up until the point a
> few days later when one (Rails?) map used Symbols and another used
> Strings.  Ouch.
>     Without any explicit typing abilities in the language (optional or
> otherwise?) it seems like the only solution is to return to basic string
> matches:
>     regex = Regexp.compile("^#{matcher.to_s}$", Regexp::IGNORECASE)
>     key = map.keys.find{ |key| key.to_s =~ regex }
> Yuck.

There's been endless discussion and confusion about Symbols, Strings,
what they mean, what they should be used for, and their relation to
each other. Rails did not help with HashWithIndifferentAccess, though
I imagine they thought they would. But I don't want to start anything
like that up. I just want to point out that a lot of that code is
unnecessary and could just be:

    key = map.keys.detect { |k|  k.to_s.downcase ==
matcher.to_s.downcase }

Specifically, "#{something.to_s}" is not required because string
interpolation calls to_s on the object. And anyway, this example seems
confused with Symbol vs. String as well as case-insensitive matching.
If you want something like that, you write your own Hash (or Map)
subclass or find something someone else wrote. Maybe there's
HashWithReallyIndifferentAccess or HashThatJustKnowsWhatYouMean or
HashThatWillGiveYouTheValueOfSomeTangentionallyRelatedKey.

> 4. And what's up with Ruby incorrectly naming their Map 'Hash'?

This isn't only a Ruby thing. I'm used to it, but then again I came to
Ruby from Perl.

At least they're not called "dictionaries", right? Am I right?

> Or is my C.S. idea of a Hash too limited?  Granted in Java they
> have HashMap, but if you enter one value and get a second one
> out it is a Map, regardless of how the keys are stored.

Hey, why aren't Arrays called Maps instead?

--
-yossef