TIL: Fun With Ruby Method Creation

Let's create a module that with a method that can wrap around another.

module Wrappable
  def log(name)
    original_method = instance_method(name)
    define_method(name) do |*args|
      puts "Calling #{name} with #{args.inspect}."
      result = original_method.bind(self).call(*args)
      puts "Completed #{name}."
      result
    end
  end
end

Now, let's create a class where we are particularly interested in wrapping one of the methods.

class Foo
  extend Wrappable

  log def add(item)
    @stuff ||=[] 
    @stuff << item
  end
end

Notice the log before the method declaration?

Foo.new.add('Bananas')
# Calling add with ["Bananas"].
# Completed add.
# => ["Bananas"]