From: Sam Smoot <ssmoot@...>
Date: 2006-09-08T08:25:07+09:00
Subject: Re: get the name of a method's parameter

This is an ugly hack, and isn't very pretty in usage, plus it's got
lots of holes I'm sure, but:

module ParameterInspector
	def self.included(base)
		base.extend ClassMethods
	end

	module ClassMethods
		def find_method_declaration(m)
			cat[/def\s+#{m}($|\(.*)/]
		end

		def find_parameter(method_name, arity)
			find_method_declaration(method_name)[/\(.*\)/][1...-1].split(',')[arity]
		end

		def cat
			File.read(self.file)
		end
	end
end

Then to use it, you must write a class that defines a ::file method,
and include it.

class Example

	include ParameterInspector

	def self.file
		__FILE__
	end

	def say(something)
		puts something
	end
end

puts Example.find_parameter :say, 0
"something"