From: James Edward Gray II <james@...>
Date: 2005-03-30T23:53:25+09:00
Subject: Defining a Class Accessor

I was playing around with an idea in another thread and ran into a 
surprise.  Can anyone explain the following to me?

irb(main):015:0> class Module
irb(main):016:1> def cattr_accessor( *symbols )
irb(main):017:2>     symbols.each do |sym|
irb(main):018:3*         eval "def self.#{sym}(  ) @@#{sym} end
irb(main):019:3"               def self.#{sym}=( value ) @@#{sym} = 
value end"
irb(main):020:3>     end
irb(main):021:2> end
irb(main):022:1> end
=> nil
irb(main):023:0> class Accessor
irb(main):024:1> cattr_accessor :one, :two
irb(main):025:1> def self.fetch_one(  )
irb(main):026:2>     @@one
irb(main):027:2> end
irb(main):028:1> end
=> nil
irb(main):029:0> Accessor.one = "James"
=> "James"
irb(main):030:0> Accessor.two = "Gray"
=> "Gray"
irb(main):031:0> Accessor.one
=> "James"
irb(main):032:0> Accessor.two
=> "Gray"
irb(main):033:0> Accessor.fetch_one
NameError: uninitialized class variable @@one in Accessor
         from (irb):26:in `fetch_one'
         from (irb):33
         from (null):0

Everything works as expected, save fetch_one().  Why does it not return 
"James"?

Thanks.

James Edward Gray II