From: Kevin Mahler <kevin.mahler@...>
Date: 2011-04-15T16:14:37+09:00
Subject: Re: looking for an "inversion" pattern

Fearless Fool wrote in post #992929:
> I'd like to create a method +foo+ that transforms:
>
>    my_obj.foo.some_method(*args)
>
> to
>
>   MyClass.some_method(my_obj, *args)

  class MyClass
    def self.some_method(obj, *args)
      puts "MyClass.some_method:"
      puts "obj: #{obj.inspect}"
      puts "args: #{args.inspect}"
    end
  end

  def define_foo(obj, clazz, method)
    obj.singleton_class.class_eval do
      define_method :foo do
        Class.new do
          define_method method do |*args|
            clazz.send(method, obj, *args)
          end
        end.new
      end
    end
  end

  my_obj = "my_obj thing"
  args = [1,2,3]
  define_foo(my_obj, MyClass, :some_method)
  my_obj.foo.some_method(*args)

  # =>
  # MyClass.some_method:
  # obj: "my_obj thing"
  # args: [1, 2, 3]

Returning facade or proxy objects like this can be an elegant solution 
to certain problems. It's rather high on the abstraction ladder, though, 
and without knowing the context I would wonder if more direct solutions 
are possible.

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