python原型模式(二)

python原型模式(二)

import copy
from collections import OrderedDict


class Book:
    def __init__(self, name, authors, price, **rest):

        '''rest的例子有:出版商、长度、标签、出版日期'''
        self.name = name
        self.authors = authors
        self.price = price  # 单位为美元
        self.__dict__.update(rest)

    def __str__(self):

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


class Prototype:
    def __init__(self):

        self.objects = dict()

    def register(self, identifier, obj):

        self.objects[identifier] = obj

    def unregister(self, identifier):

        del self.objects[identifier]

    def clone(self, identifier, **attr):

        found = self.objects.get(identifier)
        if not found:
            raise ValueError('Incorrect object identifier: {}'.format(identifier))
        obj = copy.deepcopy(found)
        obj.__dict__.update(attr)
        return obj


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()

python原型模式(二)_第1张图片

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