How do you overload the << operator in Ruby?

Question

I'm not sure how to accomplish overloading the << operator for a method. This is how I assumed it would work:

def roles<<(roles)
  ...  
end

That however, throws errors. Any suggestions?

Answer 1

You need to do that from within a class. Like this:

class Whatever
  attr_accessor :roles
  def initialize
    @roles = []
  end
  def <<(role)
     @roles << role
  end
end

You can't really have a <<roles method. You'd have to have an accessor for roles that supports the << operator.

EDIT: I've updated the code. Now you can see how the << operator should be overloaded, but you can also do what the roles<< part. Here's a small snippet of it's usage:

w = Whatever.new
w << "overload for object called"
# and overloads for the roles array
w.roles << "first role"
w.roles << "second role"