Rob Olson's blog
Update: Read the follow-up post Second thoughts on initializing modules
I was recently presented the problem of appending to the initialize method from a module that was being included. To do this it would need to override the class's initialize method with my own but keep the functionality of the original initialize method.
Whenever I need to do something in Ruby that I know will require some experimentation I like to move outside of my application and reproduce the problem in a simple way. For this problem I created a Person class that mixes in a Teacher module.
module Teacher
def initialize
puts "initializing teacher"
end
end
class Person
include Teacher
def initialize
puts "initializing person"
end
end
The goal is to get the following output when a Person object is created:
> Person.new
initializing teacher
initializing person
The basic program fails as expected; Teacher.new prints "initializing person" because Person's initialize is trumping Teacher's. Our immediate goal is to replace Person's initialize with Teacher's but in a way that preserves the original initialize method. By using alias_method we can create a copy of the original initialize method that we can call later.