From: erik blas <ether.sa@...>
Date: 2005-12-27T15:46:14+09:00
Subject: can't figure out what's wrong

I'm reading the why's ruby guide, and i've retyped a class in the guide 
to use through the metaprogramming chapter. when i try to use it with 
irb i get this error:
nomethoderror: undefined method '[]=] for nil:class
 from path/dwemthy.rb:18:in 'life'
 from path/dwemthy.rb:16:in 'life'
 from path/rabbit.rb:4

here's the code for dwemthy.rb:
class Creature

	# get a metaclass for this class
	def self.metaclass; class << self; self; end; end

	# advanced metaprogramming cord for clean traits
	def self.traits( *arr )
		return @traits if arr.empty?

		# 1. setup accessors for each variable
		attr_accessor *arr

		# 2. add a new class method to each trait
		arr.each do |a|
			metaclass.instance_eval do
				define_method( a ) do |val|
					@triats ||= {}
					@traits[a] = val
				end
			end
		end

		# 3. for each monster, the 'initialize' method should use
		#     the default number for each trait
		class_eval do
			define_method( :initialize ) do
				self.class.traits.each do |k,v|
					instance_varable_set("@#{k}", v)
				end
			end
		end

	end

	# creature attributes are read only
	traits :life, :strength, :charisma, :weapon

	# this method applies a hit taken during a fight
	def hit( damage )
		p_up = rand( charisma )
		if p_up % 9 == 7
			@life += p_up / 4
			puts "[#{ self.class } magick powers up #{ p_up }!]"
		end

		# this method takes one turn in a fight
		def fight( enemy, weapon )
			if life <= 0
				puts "[#{ self.class } is too dead to fight!]"
				return
			end

			# attack opponent
			your_hit = rand( strength + weapon )
			puts "[You hit with #{ your_hit } points of damage!]"
			enemy.hit( your_hit )

			# retaliation
			p enemy
			if enemy.life > 0
				enemy_hit = rand( eneme.strenght + enemy.weapon )
				puts "[Your enemy hit with #{ enemy_hit } points \
				of damage!] "
				self.hit( enemy_hit )
			end
		end

	end
end

class DwemthysArray < Array
	alias _inspect inspect
	def inspect; "#<#{ self.class }#{ _inspect }>"; end
	def method_missing( meth, *args )
		answer = first.send( meth, *args )
		if first.life <= 0
			shift
			if empty?
				puts "[Whoa. You decimated Dwemty's Array!]"
			else
				puts "[Get ready. #{ first.class } has emerged.]"
			end
		end
		answer || 0
	end
end

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