Totally Contrived Episode #1 - class << self

gistfile1.txt

class Foo
  class << self
    attr_accessor :a, :b
  end

  def self.register(args = {}) 
    args.each do |k,v|
      self.send(:"#{k}=", v)
    end
  end

  def self.moo
    a * b
  end
end

class FooLish < Foo
  register :a => 7, :b => 6
end

class FooNiture < Foo
  register :a => 1, :b => 2
end


puts FooLish.moo
puts FooNiture.moo

class Foo
  def self.moo(a, b)
    a * b
  end
end

Updated it to be a little more real-worldish... Not much, just a little.

class Foo
  def self.a
    6
  end

  def self.b
    7
  end

  def self.moo
    a + b
  end
end

class Boo < Foo
  def self.b
    8
  end
end

p Foo.moo #=> 13
p Boo.moo #=> 14

class Foo
  def self.register(config = {})
    config.each do |k,v|
      define_singleton_method k do
        v
      end
    end
  end

  register :a => 1, :b => 2

  def self.moo
    a * b
  end
end

class Boo < Foo
  register :b => 3
end

p Foo.moo
p Boo.moo
p Foo.moo

It's silly that you can't edit gist comments. The output of that is:

2
3
2

module StrictlyConfigurable
  def register(config = {})
    config.each do |k,v|
      define_singleton_method k do
        v
      end
    end
  end
end

class Foo
  extend StrictlyConfigurable

  register :a => 1, :b => 2

  def self.moo
    a * b
  end
end

class Boo < Foo
  register :b => 3
end

p Foo.moo
p Boo.moo
p Foo.moo

👍