90 lines
2.5 KiB
Python
90 lines
2.5 KiB
Python
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# 我们有时候想在子类中定义一些父类没有的属性进行属性拓展
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class Person:
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def __init__(self, name):
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self.name = name
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@property
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def name(self):
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return self._name
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@name.setter
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def name(self, name):
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if not isinstance(name, str):
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raise TypeError('name must be str')
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else:
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self._name = name
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@name.deleter
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def name(self):
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raise AttributeError('name cannot be deleted')
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# 我们从Person中继承,并对name属性的功能进行拓展
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class SubPerson(Person):
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@property
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def name(self):
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print("Getting name...")
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return super().name
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@name.setter
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def name(self, value):
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print("Setting name to {}...".format(value))
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super(SubPerson, SubPerson).name.__set__(self, value)
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@name.deleter
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def name(self):
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print("Deleting name...")
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super(SubPerson, SubPerson).name.__delete__(self)
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# s = SubPerson("Guido")
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# s.name
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# s.name = "Larry"
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# s.name = 42
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# 如果只是想拓展属性的其中一个方法,可以使用如下代码实现
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# 只修改setter
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class SubPerson2(Person):
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# 指定父类中属性的某种方法
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@Person.name.setter
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def name(self, value):
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print("Setting name to {}...".format(value))
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super(SubPerson2, SubPerson2).name.__set__(self, value)
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s2 = SubPerson2("Guido2")
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s2.name = "Larry"
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#只修改getter
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class SubPerson3(Person):
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# 我们也可以这样操作
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@Person.name.getter
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def name(self):
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print('Getting name .....')
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return super().name
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s3 = SubPerson3("Guido3")
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s3.name
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s3.name = "Larry"
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s3.name
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# Python3让我们太舒服了,super的本质是super(类名, self),这些参数被省略了,它的意思其实是从self的MRO列表里寻找类名的下一个位置
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# 所以这里的 super(SubPerson, SubPerson).name 其实是在SubPerson的MRO列表中寻找SubPerson的下一个类,用途是找到Person
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# 万万记住,这种方式一次只能修改一个方法,如果一次修改多个,生效的只有最后被定义的那个
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#比如这里生效的只有setter
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class SubPerson4(Person):
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# 我们也可以这样操作
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@Person.name.getter
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def name(self):
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print('Getting name .....')
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return super(SubPerson4, SubPerson4).name.__get__(self)
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@Person.name.setter
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def name(self, value):
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print("Setting name to {}...".format(value))
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super(SubPerson4, SubPerson4).name.__set__(self, value)
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s4 = SubPerson4("Guido4")
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s4.name
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s4.name = "Larry"
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s4.name
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