ruby_metaprogramming

	# class.instance_methods(false)
	class Rubyist
	# the code in the following method definition is executed later,
	# when you eventually call the method
	def what_does_he_do
	@person = 'A Rubyist'
	'Ruby programming'
	end
	end
	an_object = Rubyist.new
	puts an_object.class # => Rubyist
	puts an_object.class.instance_methods(false) # => what_does_he_do
	an_object.what_does_he_do
	puts an_object.instance_variables # => @person
	#respond_to
	obj = Object.new
	if obj.respond_to?(:program)
	obj.program
	else
	puts "Sorry, the object doesn't understand the 'program' message."
	end
	#send
	class Rubyist
	def welcome(*args)
	"Welcome " + args.join(' ')
	end
	end
	obj = Rubyist.new
	puts(obj.send(:welcome, "famous", "Rubyists")) # => Welcome famous Rubyists
	#:method_missing
	class Rubyist
	def method_missing(m, *args, &block)
	str = "Called #{m} with #{args.inspect}"
	if block_given?
	puts str + " and also a block: #{block}"
	else
	puts str
	end
	end
	end
	# => Called anything with []
	Rubyist.new.anything
	# => Called anything with [3, 4] and also a block: #<Proc:0xa63878@tmp.rb:12>
	Rubyist.new.anything(3, 4) { something }
	#http://ruby-metaprogramming.rubylearning.com/html/ruby_metaprogramming_2.html

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