From: Hugh Sasse <hgs@...>
Date: 2005-09-28T01:10:23+09:00
Subject: Re: Class and Iterator Design Question

On Wed, 28 Sep 2005, Jim Freeze wrote:

> This may be a silly design question, but I always balk at
> the right answer when I am confronted with it.
>
> I have a class that manages a list and users need to iterate over that list.
> The way I see it, I have to basic alternatives:
>
>  # Give user access to the array and let them iterate over Array
>  class Pea
>    attr_reader :pods
>  end
>  Pea.new.pods.each { |pod| ..do stuff.. }
>
Which exposes implementation somewhat, but....

> or
>
>  # Provide a custom iterator
>  class Pea
>    def each_pod
>      @pods.each { |pod| yield pod }
>    end

      # Maybe:-
      alias :each :each_pod

>  end
>  Pea.new.each_pod  { |pod| ..do stuff.. }
> end
>
> In other words, for classes that manage a list of items,
> do people prefer to see a custom iterator, such as #each_<item>,
> or do they prefer getting back an array and iterating
> over it themselves, such as #<items>.each?
>
>  Pea.new.each_pod  { |pod| ..do stuff.. }
>  Pea.new.pods.each { |pod| ..do stuff.. }

I'd expect
    Pea.new.each{ |pod| ... ]

because you might change your list to a Set or tree or soemthing
later. Unless you normally iterate over something else... 
(But having said that, I'd expect a Pod to contain Peas :-)!)
>
> Cheers
> --
> Jim Freeze
>
>
         Hugh