gistfile1.rb

require 'alias_dci'   
class A
  include AliasDCI::DataObject
  def foo
    "a"
  end
end

class C
  include AliasDCI::Context # No need to also include DataObject in a context, it is one anyway

  role :y do
    contract :foo
  end
  
  role :z do
    def foo
      "z"
    end
  end
  def initialize(some_t, some_k)
    assign_named_roles(:y => some_t, :z => some_k)
  end

  def print
    in_context do
      puts "foo of y " + (r_y.foo.to_s)   # explictly using r_rolename as the label as role y, requires instance #foo.
      puts "foo of z " + (z.foo.to_s)
    end
  end
  
  def foo
    "context"
  end
  
  def rebind(a)
    assign_named_roles(:y => a, :z => self)   # initialize is only really called on Class#new, its kinda Ruby's constructor method
    print
    assign_named_roles(:y => self, :z => a)
  end
end

def do_it(some_t, some_k)
  c = C.new(some_t, some_k)
  c.print
  c.rebind(some_t)
  c.print
end

a = A.new
do_it(a, a)

# => nil
# outputs : 
# >> foo of y a
# >> foo of z z
#each object is only playing one role
# >> foo of y a
# >> foo of z z
#again one role for each object
# >> foo of y context
# >> foo of z z

#matches this :
#foo of y a
#foo of z z
#foo of y a
#foo of z z
#foo of y context
#foo of z z