From: Trans <transfire@...>
Date: 2007-01-23T05:39:46+09:00
Subject: Re: Hash pairs at?


Joel VanderWerf wrote:
> Alex LeDonne wrote:
> > Maybe I'm late to the party, but instead of select_pair, I'd name the
> > method slice, analagous to Array#slice.
>
> Looks like the rails crowd has beaten us to it:
>
> http://dev.rubyonrails.org/changeset/5726
>
> It might be in facets, too.
>
> Seems like a good name for a good method.

hmm... in Facets, Hash#slice is just an alias for Hash#values_at.
#slice is a reasonably good name. however I suggested #select_pair, not
as a name for #pairs_at, but as a hash equivalent of #select, to enrich
the langauge with greater polymorphism between hash and asscocivtive
arrays.

  {:a=>1, :b=>2}.select{ |k,v| k == :a } #=>  [[:a=>1]]
  [ [:a, 1], [:b, 2] ].select{ |k,v| k == :a } #=>  [[:a=>1]]

  {:a=>1, :b=>2}.select_pair{ |k,v| k == :a } #=>  { :a=>1 }
  [ [:a, 1], [:b, 2] ].select_pair{ |k,v| k == :a } #=>  { :a=>1 }

Most of the normal enumerable each-related methods could have hash
equivalents like this.

(I'm not partial to the _pair suffix, but for lack of a better term...)

T.