How to mixin some class methods and some instance methods from a module in Ruby?

I have a module and would like to mixin some methods as class methods and some as instance methods.

For example:

module Foo
  def self.class_method
  end

  def instance_method
  end
end

class Bar
  include Foo
end

Usage:

Bar.class_method
Bar.new.instance_method

Is it possible to do this in Ruby?

If not, is it possible to define which methods are class methods and which are instance methods within the Bar class?

I don't want the same method defined as both a class and instance method.

Solution

This pattern is very common in Ruby. So common, in fact, that ActiveSupport::Concern abstracts it a bit.

Your typical implementation looks like this:

module Foo
  def self.included(other_mod)
    other_mod.extend ClassMethods
  end

  def instance_method
  end

  module ClassMethods
    def class_method
    end
  end
end

class Bar
  include Foo
end

You can't accomplish this easily as you describe without somehow splitting the included module into multiple pieces, though, unfortunately.