Oh it was really easy:
module RolePatch
module InstanceMethods
private <<<<<<<<<<<<<<<<<<<<<<<<<<<< It works like a charm.
def my_private_method; end
end
def self.included(receiver)
receiver.send :include, InstanceMethods
receiver.class_eval do
after_create :my_private_method
end
end
end
1.9.3p392 :017 > Role.first.private_methods.grep(/my_private_method/)
=> [:my_private_method]
So we can use private modifier in module InstanceMethods
as usual.