From: John Carter <john.carter@...>
Date: 2005-04-20T12:43:00+09:00
Subject: Lookup, a.collect{|i|b[i]}

# Rubyable email..
#I suspect there is a standard trick for this, but can't spot it now...

a = [3,6,3,1,6] # Arbitary Array of stuff
b = [1,2,3,4,5,6,7,8,9,0] # Could be Array or Hash, don't care.
p a.collect{|i|b[i]}
# Outputs...
#[4, 7, 4, 2, 7]

# I vaguely feel that there should be a standard method "lookup" and 
# perhaps a standard module Indexable.
# Like module Enumerable assumes there exists an "each" method,
# module Indexable assume it's including class has an [] method.
module Indexable
   def lookup(*ary)
     ary.collect{|i| self[i]}
   end
end

class Array
   include Indexable
end

class Hash
   include Indexable
end

p b.lookup( 3,6,3,1,6)
# outputs...
#[4, 7, 4, 2, 7]

h = {'tom'=>1, 'dick'=>2, 'harry'=>3}
p h.lookup(*%w{tom tom dick harry dick})
# Outputs...
#[1, 1, 2, 3, 2]

#John Carter                             Phone : (64)(3) 358 6639
#Tait Electronics                        Fax   : (64)(3) 359 4632
#PO Box 1645 Christchurch                Email : john.carter@tait.co.nz
#New Zealand

#Refactorers do it a little better every time.