Metaprogramming Ruby 2

method_missing

Where you listen to spooky stories about Ghost Methods and dynamic proxies and you try a second way to remove duplicated code.

With Ruby, there’s no compiler to enforce method calls. This means you can call a method that doesn’t exist. For example:

methods/method_missing.rb

class Lawyer; end
nick = Lawyer.new
nick.talk_simple

NoMethodError: undefined method `talk_simple' for #<Lawyer:0x007f801aa81938>

Do you remember how method lookup works? When you call talk_simple, Ruby goes into nick’s class and browses its instance methods. If it can’t find talk_simple there, it searches up the ancestors chain into Object and eventually into BasicObject.

Because Ruby can’t find talk_simple anywhere, it admits defeat by calling ...