From: Trans <transfire@...>
Date: 2007-01-22T03:12:41+09:00
Subject: Re: Hash pairs at?


Robert Dober wrote:

> I'd rather see it in the core
> I have a slight preference for  #pairs_at, #entries is not a bad name, but I
> feel the first is more descriptive.

I agree. I think #paris_at is easier to quicky comprehend.

Also, I recalled I had added another method to facets that can do this
too. I was writing Hash#| and thought I should go ahead and wrote an #&
too if reasonable. And lo! There it was:

  h = {:a=>1,:b=>2,:c=>3}
  h & [:a,:b]  #=> {:a=>1,:b=>2}

Code for facets/core/hash/op_and.rb (also op_or.rb):

  class Hash
    def &(other)
      case other
      when Array
        k = (keys & other)
        Hash[*(k.zip(values_at(*k)).flatten)]
      else
        Hash.new[*(to_a & other.to_a).flatten]
      end
    end

    def |(other)
      other.merge self
    end
  end

Think I still prefer the readability of #pairs_at however. But the
above is good to have too.

T.