38 lines
1.4 KiB
Python
38 lines
1.4 KiB
Python
class Typed:
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def __init__(self, key, expected_type): # 构造函数接收所传入的参数和参数类型
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self.key = key
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self.expected_type = expected_type
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def __get__(self, instance, owner):
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print('get方法')
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return instance.__dict__[self.key] # 从底层字典获取值
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def __set__(self, instance, value):
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print('set方法')
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if not isinstance(value, self.expected_type): # 类型判断
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raise TypeError('%s 传入的类型不是%s' % (self.key, self.expected_type)) # 格式化抛出异常
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instance.__dict__[self.key] = value # 修改底层字典
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def __delete__(self, instance):
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print('delete方法')
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instance.__dict__.pop(self.key)
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class People:
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name = Typed('name', str) # p1.__set__() self.__set__()，触发描述符__set__方法，设置参数类型传给构造函数
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age = Typed('age', int) # p1.__set__() self.__set__()
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salary = Typed('salary', float) # p1.__set__() self.__set__()
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def __init__(self, name, age, salary):
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self.name = name
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self.age = age
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self.salary = salary
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# p1=People('alex','13',13.3)#类型有误，报错
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p1 = People('alex', 13, 13.3)
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print(p1.__dict__)
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print(p1.name)
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p1.name = 'egon'
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print(p1.__dict__)
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del p1.name
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print(p1.__dict__)
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# print(p1.name) # 相应的键值对已在底层字典中删除了，报错 |