From: "Schüle Daniel" <uval@...>
Date: 2006-02-02T06:41:29+09:00
Subject: local variable and closure

Hello,

below is one little script that fails at ### <<< line
the output is

Animal has properties
Animal will be speakable
Dog has properties
Dog will be speakable
Duck has properties
Duck will be speakable
../dort.rb:16:in `speak': undefined local variable or method `msg' for 
#<Dog:0x401d8da0> (NameError)
         from ./dort.rb:44

I would think that (passed to function) local variable msg would be 
"closed" in self.class_eval {} closure and therefor be accessable

can someone point out why it doesn't work?

Regards, Daniel


#!/usr/bin/env ruby

$prop = {}

def prop
	puts "#{self.name} has properties"
	self.class_eval do
		$prop[self] = []
	end
end

def speakable(msg)
	puts "#{self.name} will be speakable"
	self.class_eval do
			$prop[self] << "I can speak"
			def speak;msg;end		### <<<
	end
end

class Animal
	prop
	speakable "..."
	def whatCanIDo;$prop[self.class];end
	def self.whatCanIDo;$prop[self];end
end

class Dog < Animal
	prop
	speakable "wuff"
end

class Duck < Animal
	prop
	speakable "quak"
end

a = Dog.new
b = Duck.new

puts a.speak, b.speak