NAME
  arrayfields.rb

URIS
  http://www.codeforpeople.com/lib/ruby/
  http://rubyforge.org/projects/codeforpeople/

SYNOPSIS
    require 'arrayfields'

    a = Arrayfields.new :k, :v, :a, :b

    p a[:k]        #=> :v
    p a[:a]        #=> :b
    p a.fields     #=> [:k, :a]
    p a.values     #=> [:v, :b]
    p a            #=> [:v, :b]
    p a.to_hash    #=> {:k => :v, :a => :b} 
    p a.pairs      #=> [[:k, :v], [:a, :b]]

    a[:foo] = :bar

    p a[:foo]      #=> :bar
    p a.fields     #=> [:k, :a, :foo]

 AND

    require 'arrayfields'  

    fields = 'name', 'age'
    a = [ 'zaphod', 42 ]

    a.fields = fields

    a['name']                #=> 'zaphod'
    a[:name ]                #=> 'zaphod'
    a.indices 'name', 'age'  #=> [ 'zaphod', 42 ]

DESCRIPTION
  allow keyword access to array instances.  arrayfields works by adding only a
  few methods to arrays, namely #fields= and fields, but the #fields= method is
  hooked to extend an array on a per object basis.  in otherwords __only__ those
  arrays whose fields are set will have auto-magical keyword access bestowed on
  them - all other arrays remain unaffected.  arrays with keyword access require
  much less memory when compared to hashes/objects and yet still provide fast
  lookup and preserve data order.

LIST OF OVERRIDDEN METHODS
  Array#[]
  Array#slice
  Array#[]=
  Array#at
  Array#delete_at
  Array#fill
  Array#values_at
  Array#indices
  Array#indexes
  Array#slice!

LIST OF HASH-LIKE METHODS
  Array#each_with_field
  Array#each_pair
  Array#each_key
  Array#each_value
  Array#fetch
  Array#has_key?
  Array#member?
  Array#key?
  Array#has_value?
  Array#value?
  Array#keys
  Array#store
  Array#values
  Array#to_hash
  Array#to_h
  Array#update
  Array#replace
  Array#invert
  Array#pairs

LIST OF ADDED Array METHODS
  Array#fields=
  Array#fields

LIST OF ADDED Array CLASS METHODS
  Array.fields/Array.struct

SAMPLES

  <========< sample/a.rb >========>

  ~ > cat sample/a.rb

    require 'arrayfields'
    #
    # the class Array has only a few added method, one is for setting the fields,
    # when the fields are set for an array THIS INSTANCE ONLY will be modified to
    # allow keyword access.  other arrays will not be affected!
    #
      a = [0,1,2]
      fields = ['zero', 'one', 'two']
      a.fields = fields                # ONLY the Array 'a' is affected!
    #
    # keyword access is now allowed for many methods
    #
      p a['zero']                        #=> 0
      p a['one']                         #=> 1
      p a['two']                         #=> 2
      p a.at('one')                      #=> 1
      p a.values_at('zero', 'two')       #=> [0, 2]
    #
    # assigmnet is allowed
    #
      a['zero'] = 42
      p a['zero']                        #=> 0
      a['zero'] = 0 
    #
    # assignment to non-fields results in the element being appended and the field
    # being added for future use (also appended)
    #
      p(a.fields.join(','))                 #=> "zero, one, two"
      p a['three']                          #=> nil
      a['three'] = 3
      p(a.fields.j