extend self

extend_self.rb

# A friend of mine Stuart (https://github.com/stuartc) and I discussed this today.
# I think `extend self` adds the classes to the eigenclass of the module, or the eigenmodule? Whatever.

# My code used to look like

class BusinessBusiness
  def initialize(foo, bar)
    @foo = foo
    @bar = bar
  end
  
  def call
    do_some_things_with_foo_and_bar
  end
end

biz = BusinessBusiness.new("foo", "bar")
budget = biz.call

# Now I prefer stateless modules

module BusinessBusiness
  extend self
  
  # pure
  def something_descriptive(foo, bar)
    foo + bar
  end
end

budget = BusinessBusiness.something_descriptive("foo", "bar")

# You can also grab the method object to pass around

budget_maker = BusinessBusiness.method(:something_descriptive)
budget_maker.call("foo", "bar")
# or
budgets = OtherService.construct_budgets(budget_maker, ["data", "456", "pew pew"])