Python 原型模式

原型设计模式有助于隐藏类创建的实例的复杂性。现有对象的概念与从头创建的新对象的概念不同。

如果需要，新复制的对象的属性可能会有一些更改。这种方法可以节省开发产品所需的时间和资源。

1. 如何实现原型模式？

现在让我们看看如何实现原型模式。

# Filename : example.py
# Date : 2020-08-22
import copy
class Prototype:
    _type = None
    _value = None
    def clone(self):
        pass
    def getType(self):
        return self._type
    def getValue(self):
        return self._value
class Type1(Prototype):
    def __init__(self, number):
        self._type = "Type1"
        self._value = number
    def clone(self):
        return copy.copy(self)
class Type2(Prototype):
    """ Concrete prototype. """
    def __init__(self, number):
        self._type = "Type2"
        self._value = number
    def clone(self):
        return copy.copy(self)
class ObjectFactory:
    """ Manages prototypes.
    Static factory, that encapsulates prototype
    initialization and then allows instatiation
    of the classes from these prototypes.
    """
    __type1Value1 = None
    __type1Value2 = None
    __type2Value1 = None
    __type2Value2 = None
    @staticmethod
    def initialize():
        ObjectFactory.__type1Value1 = Type1(1)
        ObjectFactory.__type1Value2 = Type1(2)
        ObjectFactory.__type2Value1 = Type2(1)
        ObjectFactory.__type2Value2 = Type2(2)
    @staticmethod
    def getType1Value1():
        return ObjectFactory.__type1Value1.clone()
    @staticmethod
    def getType1Value2():
        return ObjectFactory.__type1Value2.clone()
    @staticmethod
    def getType2Value1():
        return ObjectFactory.__type2Value1.clone()
    @staticmethod
    def getType2Value2():
        return ObjectFactory.__type2Value2.clone()
def main():
    ObjectFactory.initialize()
    instance = ObjectFactory.getType1Value1()
    print("%s: %s" % (instance.getType(), instance.getValue()))
    instance = ObjectFactory.getType1Value2()
    print("%s: %s" % (instance.getType(), instance.getValue()))
    instance = ObjectFactory.getType2Value1()
    print("%s: %s" % (instance.getType(), instance.getValue()))
    instance = ObjectFactory.getType2Value2()
    print("%s: %s" % (instance.getType(), instance.getValue()))
if __name__ == "__main__":
    main()

输出

上面的程序将产生以下输出-

Type1: 1
Type1: 2
Type2: 1
Type2: 2

输出有助于使用现有对象创建新对象，并且在上述输出中清晰可见。