Main part of prototype_pattern.py

book.py

class Book:
  def __init__(self, name, authors, price, **rest):
    '''Examples of rest: publisher, length, tags, publication date'''
    self.name = name
    self.authors = authors
    self.price = price
    self.__dict__.update(rest)

  def __str__(self): 
    mylist=[]
    ordered = OrderedDict(sorted(self.__dict__.items())) for i in ordered.keys():
    if i == 'price': mylist.append('RM ')
                   mylist.append('{}: {}'.format(i, ordered[i]))
    mylist.append('\n') return ''.join(mylist)

prototype_pattern_main.py

def main():
    b1 = Book('The C Programming Language',('Brian W. Kernighan', 'Dennis M.Ritchie'),price=118, publisher='Prentice Hall', length=228,publication_date='1978-02-22',tags=('C', 'programming', 'algorithms', 'data structures'))

    prototype = Prototype()
    cid = 'k&r-first'
    prototype.register(cid, b1)
    b2 = prototype.clone(cid, name='The C Programming Language (ANSI)', price=48.99, length=274, publication_date='1988-04-01', edition=2)

    for i in (b1, b2):
        print(i)
    
    print("ID b1 : {} != ID b2 : {}".format(id(b1), id(b2)))

if __name__ == '__main__':
    main()