Dynamically overwrite methods

class_methods.rb

class Frog
  def self.go
    puts 45
  end
end

Frog.go

module Whatever

  def self.extended(base)
    (class << base; self; end).send(:alias_method, :go, :new_go)
  end

  def new_go
    puts 99
  end

end

Frog.send(:extend, Whatever)

Frog.go

instance_methods.rb

class Frog
  def go
    puts 45
  end
end

Frog.new.go

module Whatever

  def self.included(base)
    base.send(:alias_method, :go, :new_go)
  end

  def new_go
    puts 99
  end

end

Frog.send(:include, Whatever)

Frog.new.go