Method Objects and Aliasing

class_vs_module.rb

class Person
  def greet(name)
    "Hello, #{name}!"
  end
end
Person.instance_method(:greet).bind(Object.new)["World"] 
#=> TypeError: bind argument must be an instance of Person

module Greeter
  def greet(name)
    "Hello, #{name}"
  end
end
Greeter.instance_method(:greet).bind(Object.new)["World"]
#=> "Hello, World!"

#-------------------------------------------------------------------------------

module Greeter
  def greet(name)
    "Hello, #{name}"
  end
end

class Person
  include Greeter
end
Person.instance_method(:greet).bind(Object.new)["World"] 
#=> TypeError: bind argument must be an instance of Person

spy.rb

module Spy
  def hello
    @name
  end
end

class Person
  def initialize(name)
    @name = name
  end
end

delba = Person.new('delba')
spy = Spy.instance_method(:hello)

spy.bind(delba).call #=> delba

trashable_via_alias.rb

module Trashable
  def destroy
    'hacked destroy'
  end
end

class ActiveRecord::Base
  def self.acts_as_trashable
    alias destroy! destroy #=> :destroy == ActiveRecord::Base.instance_method(:destroy)
    # alias_method :destroy!, :destroy => :destroy == ActiveRecord::Base.instance_method(:destroy)
    include Trashable
    # alias destroy! destroy => :destroy == ActiveRecord::Base.instance_method(:destroy)
    # alias_method :destroy!, :destroy => :destroy == Paranoia.instance_method(:destroy)
  end
  
  def destroy
    'original destroy'
  end
end

class HulaHoop < AR
  acts_as_trashable
end

hula_hoop = HulaHoop.new
hula_hoop.destroy  #=> 'hacked destroy'
hula_hoop.destroy! #=> 'original destroy'

trashable_via_method_object.rb

module Trashable
  def destroy
    'hacked destroy'
  end
  
  def destroy!
    ActiveRecord::Base.instance_method(:destroy).bind(self).call
  end
end

class ActiveRecord::Base
  def destroy
    'original destroy'
  end
end

class HulaHoop < ActiveRecord::Base
  include Trashable
end

hula_hoop = HulaHoop.new
hula_hoop.destroy  #=> 'hacked destroy'
hula_hoop.destroy! #=> 'original destroy'