python 設計模式

單例---類方法方式

<code>class Single():
    def __init__(self, name):
        self.name = name
    @classmethod
    def instance(cls, *args, **kwargs):
        if not hasattr(Single, "_instance"):
            Single._instance = Single(*args, **kwargs)
        return Single._instance
s1 = Single.instance('Gage')
s2 = Single.instance()
print(s1)
print(s2)/<code>

單例---new方式

<code>class Single(object):
    __isstance = None
    __first_init = False
    def __new__(cls, *args, **kwargs):
        if not cls.__isstance:
            cls.__isstance = object.__new__(cls)
        return cls.__isstance
    def __init__(self, name):
        if not self.__first_init:
            self.name = name
            Singleton.__first_init = True
a = Single('a')
b = Single('b')
print(id(a))
print(id(b))/<code>

工廠模式

<code># 首先定義一個抽象基類
class CarStore(object):

    # 定義生產汽車的方法
    def createcar(self, name):
        pass

    # 根據類型去生產車
    def order(self, name):
        self.car = self.createcar(name)
        self.car.move()


# 定義4s店  實現抽象類
class AoDiCarStore(CarStore):

    def createcar(self, name):
        self.factory = CarFactory()
        return self.factory.createcar(name)


# 創建一個車
class AoDi():
    def move(self):
        print('移動')
# 定義一個工廠
class CarFactory():
    def createcar(self, name):
        self.name = name
        if self.name == 'AoDi':
            self.car = AoDi()
        return self.car
aodi = AoDiCarStore()
aodi.order('AoDi')/<code>

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關鍵字: Python 單例 設計模式