From: Phil Tomson <rubyfan@...>
Date: 2006-07-07T09:36:16+09:00
Subject: Re: quick metaprogramming question: collecting arguments across calls

On 7/6/06, William Morgan <wmorgan-ruby-talk@masanjin.net> wrote:
> Hi all,
>
> Quick question: is there a better way to write Foo.contains below?
> Forcing the lexical scoping like this feels wrong.
>
> class Foo
>  def self.contains *o
>    @contents ||= []
>    @contents += o
>    contents = @contents
>    define_method(:contents) { contents }
>  end
> end
>
> class Bar < Foo
>  contains :goat, :boat
>  contains :stoat
> end
>
> p Bar.new.contents # => [:goat, :boat, :stoat]
>

How about:

 class Foo
   class << self
     def contains *o
       @contents ||= []
       @contents += o
     end
     attr_accessor :contents
   end
   def contents
     @contents ||= self.class.contents
   end
 end

 class Bar < Foo
   contains :goat, :boat
   contains :stoat
 end

 p Bar.new.contents #=> [:goat, :boat, :stoat]