From: ara.t.howard@...
Date: 2006-08-16T01:17:55+09:00
Subject: Re: Hash#each

On Wed, 16 Aug 2006, Trans wrote:

>
> phrogz@gmail.com wrote:
>> Is this whole facet just to avoid typing two extra characters in the
>> case where you don't care about the keys? Using standard Ruby 1.8.4
>> without facets:
>>
>> foo = { :name=>"Gavin", :age=>33 }
>> foo.each{ |_,v| p v }
>> #=> "Gavin"
>> #=> 33
>
> Actually an interesting question. This is one of the earliest facets in
> the library. It came out of a discussion with David Black, Matz and
> others about Polymorphic behavior between Array and Hash. If we
> considered a Hash's key analogous to an Array's index than one case see
> how this definition of #each supports that "meshing", eg.
>
>  x = [ :a, :b ]
>  x.each { |v| p v }
>  x = { 1 => :a, 2 => :b }
>  x.each { |v| p v }
>
> See how both array and the hash produce the same result wihtout haveing
> to alter the #each statments. You can't currently do that. So this
> hash#each method was created more as an "idealistic" expirement of this
> concept, then for practical applicaiton --which explain why it
> overrides #each vs. using each_value.
>
> I still think it has merit, but as an extension it does have the
> potential of breaking other code. So I probably should get rid of it
> --and I've known it. But I've sort of left it there as a reminder of
> this interesting topic --and indeed it worked! ;-)

i'm totally with the concept of hash/array interchangeability in some
circumstances - but i think going the other way is easier:

     harp:~ > cat a.rb
     require 'rubygems'
     require 'arrayfields'

     (tuple = %w( ara howard 123 34 )).fields = %w( first_name last_name ssn age )

     p tuple['first_name']

     p tuple.values_at('ssn', 'age')

     tuple.each_pair{|k,v| p k => v}

     tuple.each{|v| p v}

     p tuple.join(',')



     harp:~ > ruby a.rb
     "ara"
     ["123", "34"]
     {"first_name"=>"ara"}
     {"last_name"=>"howard"}
     {"ssn"=>"123"}
     {"age"=>"34"}
     "ara"
     "howard"
     "123"
     "34"
     "ara,howard,123,43"


food for thought.

cheers.

-a
-- 
to foster inner awareness, introspection, and reasoning is more efficient than
meditation and prayer.
- h.h. the 14th dali lama