From: Rick DeNatale <rick.denatale@...>
Date: 2007-03-27T07:18:19+09:00
Subject: Re: Hash#map_pairs

On 3/24/07, jeff_alexander_44@yahoo.com <jeff_alexander_44@yahoo.com> wrote:
> class Hash
>    def map_pairs
>       result = Array.new
>       self.each_pair { |k, v|
>          result << yield(k, v)
>       }
>       result
>    end
> end
>
> h = {
>    "a" => "x",
>    "b" => "y",
> }
> puts h.map_pairs { |k, v| "#{k} => #{v}" }.join(", ")
>
> I was surprised to discover there was no Hash#map_pairs.  I have found
> that chaining transformations is usually better than the
> iterative/imperative style implied by Hash#each_pair.
>

In Ruby 1.9 , at least as it stands today, 'each-like' methods like
each_pair will return an Enumerator if you don't give them a block,
this allows a nice ability to chain transformations.

rick@frodo:/public/rubysource/ruby1.8.5$ irb1.9
irb(main):001:0> {:a => 1, :b => 2}.each_pair
=> #<Enumerable::Enumerator:0xb7bd2650>
irb(main):002:0> {:a => 1, :b => 2}.each_pair.map {|k,v| [v,k]}
=> [[2, :b], [1, :a]]
irb(main):003:0>


-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/