Ruby include module's single method in model

Question

I have a module of following

module SimpleTask
    def task1
    end
    def task2
    end
    def task3
    end
end

And I have a model which r

Answer 1

I'm going to steal an example from delegate.rb, it restricts what it includes

...
class Delegator < BasicObject
  kernel = ::Kernel.dup
  kernel.class_eval do
    [:to_s,:inspect,:=~,:!~,:===,:<=>,:eql?,:hash].each do |m|
      undef_method m
    end
  end
  include kernel
...

becomes

module PreciseInclude

  def include_except(mod, *except)
    the_module = mod.dup
    the_module.class_eval do
      except.each do |m|
        remove_method m # was undef_method, that prevents parent calls
      end
    end
    include the_module
  end
end

class Foo
  extend PreciseInclude

  include_except(SimpleTask, :task1, :task2)
end

Foo.instance_methods.grep(/task/) => [:task3]

you can always flip it so instead of include it becomes include_only

The catch is that remove_method won't work for nested modules, and using undef will prevent searching the entire hierarchy for that method.