From: Jim Weirich <jim@...>
Date: 2004-08-04T04:37:27+09:00
Subject: Re: Closure question


Jim Weirich said:
> The proc (i.e. closure) doesn't get defined until the second time count is
> called.  By that time, the counter variable is long out of scope (the body
> of a "def" does not form a closure, so the counter variable is not in
> scope when the proc is evaluated).

So the obvious answer is: Don't use a "def" to redefine count.  Use
"define_method" which takes a closure/block as the method body.

def count
  counter = 1
  self.class.send(:define_method, :count) { counter += 1 }
  counter
end

p count #=> 1
p count #=> 2
p count #=> 3

-- 
-- Jim Weirich     jim@weirichhouse.org    http://onestepback.org
-----------------------------------------------------------------
"Beware of bugs in the above code; I have only proved it correct,
not tried it." -- Donald Knuth (in a memo to Peter van Emde Boas)