Question

In Ruby 1.9.2 you can inspect the parameters of any method using method(:symbol). How could I inspect the Car#initialize method without having to create a new car?

class Car
  def initialize(fuel_type, passenger_capacity, door = 3)
    puts "TODO"
  end
end

Car.new(nil,nil).method(:initialize).parameters
  #=> [[:req, :fuel_type], [:req, :passenger_capacity], [:opt, :door]]

Instance_eval didn’t work:

Car.instance_eval { |x| p x.method(:initialize).parameters } #=> [[:rest]]

Answer 1

Car.instance_method(:initialize).parameters
# => [[:req, :fuel_type], [:req, :passenger_capacity], [:opt, :door]]