Where is the ruby module self.included and self.extended behaviour documented?

Question

I was looking at the ruby mixin blog post, and it says that when a module is included in a class its self.included() method is called.

My question is, where is this behaviour officially documented? I can't seem to locate it on the ruby-docs.org website or the pickaxe.

Answer 1

While it's not on Ruby Doc for some reason, included actually is documented. Running ri Module.included in the terminal provides this:

included( othermod )

---

Callback invoked whenever the receiver is included in another module or class. This should be used in preference to Module.append_features if your code wants to perform some action when a module is included in another.

module A
  def A.included(mod)
    puts "#{self} included in #{mod}"
  end
end
module Enumerable
  include A
end

This documentation can be found in the Ruby source in object.c. Sadly, Module.extended is not documented.

Answer 2

I suspect it's not on the RubyDoc website because it's a private method, and private methods aren't currently displayed.

People are aware of this issue, but they haven't yet worked out how to handle methods that are private even though they aren't implementation details.

I've created a bug report at http://bugs.ruby-lang.org/issues/6381