method_object.rb

class MethodObject < Module
  DEFAULT_NAME = :call
  
  def initialize(name = DEFAULT_NAME)
    @name = name
  end

  def self.included(host)
    host.instance_exec(@name) do |name|
      define_method :call do |*args|
        new(*args).public_send(name)
      end
    end
  end
end

class Greeter
  include Concord.new(:entity)
  include MethodObject.new
  def call
    puts("Hello #{entity}")
  end
end

Greeter.call('world')

class Printer
  include Concord.new(:text)
  include MethodObject.new(:print)
  def print
    puts("Hello #{text}")
  end
end

Printer.print('world')

My MethodObject is a littlebit differend:

class MethodObject < Module
  include Concord.new(:name)

  def self.included(host)
     name = self.name
     host.class_eval do
        def self.call(*arguments)
           new(*arguments).publi_send(name)
        end
     end
  end
end

class Foo
   include MethodObject.new(:bar)

   def bar
      :baz
   end
end # Foo

Foo.call # => :baz

The idea is to delegate to a public interface of the instance. While the arguments to the method object will end up as state of the method object.