From: Sean O'Dell <sean@...>
Date: 2004-07-01T05:07:52+09:00
Subject: Re: [ANN] arrayfields-3.0.0

On Wednesday 30 June 2004 12:32, Ara.T.Howard wrote:
> On Thu, 1 Jul 2004, Sean O'Dell wrote:
> > Ara, any chance of getting arrayfields to not modify the Array methods
> > but instead simply add an accessor to Array which returns an object that
> > encapsulates this new functionality?
> >
> > So, instead of saying:
> >
> > row = ['bob', 30]
> > row.fields = ['name', 'age']
> > row['name'] #=> 'bob'
> >
> > you would say something like:
> >
> > row = ['bob', 30]
> > row.arrayfields.fields = ['name', 'age']
> > row.arrayfields['name'] #=> 'bob'
> >
> > My thinking is that if arrayfields functionality were contained in its
> > own object that linked back to a parent array, you could create
> > arrayfield objects and attach them to other "array-like" objects, such as
> > database rows and so on.
> >
> > But also, it might prevent problems that arise later from taking over
> > Array's methods where people want to use both arrayfields, and regular
> > Array functionality.
>
> well - theoretically you lose zero Array functionality since ArrayFields
> methods are used if, and only if, the idx paramter is a String or Symbol
> which would never be done with a normal Array.
>
> that being said:
>
>    jib:~/shared > cat a.rb
>    require 'arrayfields'
>
>    class FieldedArray
>      attr :fieldset
>      def initialize fields, array
>        @a = array
>        self.fields = fields
>      end
>      def method_missing(meth, *args, &block)
>        @a.send(meth, *args, &block)
>      end
>      def fields= fields
>        extend ArrayFields unless defined? @fieldset
>
>        @fieldset =
>          if ArrayFields::FieldSet === fields
>            fields
>          else
>            ArrayFields::FieldSet.new fields
>          end
>      end
>      attr_reader :fieldset
>      def fields
>        @fieldset and @fieldset.fields
>      end
>    end
>
>    fa = FieldedArray.new %w(zero one two), [0, 1, 2]
>    fa.each_with_field{|e, f| puts "#{ f } : #{ e }"}
>
>    jib:~/shared > ruby a.rb
>    zero : 0
>    one : 1
>    two : 2
>
>
> i can't bloody believe that worked - go matz!
>
> what'ya think of adding the above to 3.3.0 (along with gem spec)?

I like your solution above where none of the arrayfields code goes directly 
into the Array class.  Benefits: no overhead for Arrays that don't use the 
arrayfields feature, and the ability to work with other objects that aren't 
Array's but which have array-like functionality.

	Sean O'Dell