你可以使用神奇的方法__getattribute__和__setattr__。

class MyClass:
    def __init__(self, attrvalue):
        self.myattr = attrvalue
    def __getattribute__(self, attr):
        if attr == "myattr":
            #Getter for myattr
    def __setattr__(self, attr):
        if attr == "myattr":
            #Setter for myattr

注意__getattr__和__getattribute__是不同的。__getattr__只在未找到属性时调用。

python使用getter和setter的方法是什么?

“Pythonic”的方法不是使用“getter”和“setter”，而是使用简单的属性，就像问题所演示的那样，以及del用于删除(但是为了保护无辜的人，更改了名称……内置命令):

value = 'something'

obj.attribute = value  
value = obj.attribute
del obj.attribute

如果稍后，你想修改设置和获取，你可以这样做，而不必修改用户代码，通过使用属性装饰器:

class Obj:
    """property demo"""
    #
    @property            # first decorate the getter method
    def attribute(self): # This getter method name is *the* name
        return self._attribute
    #
    @attribute.setter    # the property decorates with `.setter` now
    def attribute(self, value):   # name, e.g. "attribute", is the same
        self._attribute = value   # the "value" name isn't special
    #
    @attribute.deleter     # decorate with `.deleter`
    def attribute(self):   # again, the method name is the same
        del self._attribute

(每次使用装饰器都会复制并更新前面的属性对象，因此请注意，您应该为每个set、get和delete函数/方法使用相同的名称。)

在定义了上面的代码之后，原来的设置、获取和删除代码是一样的:

obj = Obj()
obj.attribute = value  
the_value = obj.attribute
del obj.attribute

你应该避免这样做:

def set_property(属性,值): def get_property(财产):

首先，上面的方法不起作用，因为你没有为属性将要设置为的实例提供参数(通常是self)，即:

class Obj:

    def set_property(self, property, value): # don't do this
        ...
    def get_property(self, property):        # don't do this either
        ...

其次，这重复了两个特殊方法__setattr__和__getattr__的目的。

第三，我们还有setattr和getattr内置函数。

setattr(object, 'property_name', value)
getattr(object, 'property_name', default_value)  # default is optional

@property装饰器用于创建getter和setter。

例如，我们可以修改设置行为来限制正在设置的值:

class Protective(object):

    @property
    def protected_value(self):
        return self._protected_value

    @protected_value.setter
    def protected_value(self, value):
        if acceptable(value): # e.g. type or range check
            self._protected_value = value

一般来说，我们希望避免使用属性，而只是使用直接属性。

这是Python用户所期望的。遵循最小惊喜原则，你应该尽量满足用户的期望，除非你有非常令人信服的相反理由。

示范

例如，我们需要我们的对象的protected属性是一个0到100之间的整数，并防止它的删除，用适当的消息告知用户它的正确用法:

class Protective(object):
    """protected property demo"""
    #
    def __init__(self, start_protected_value=0):
        self.protected_value = start_protected_value
    # 
    @property
    def protected_value(self):
        return self._protected_value
    #
    @protected_value.setter
    def protected_value(self, value):
        if value != int(value):
            raise TypeError("protected_value must be an integer")
        if 0 <= value <= 100:
            self._protected_value = int(value)
        else:
            raise ValueError("protected_value must be " +
                             "between 0 and 100 inclusive")
    #
    @protected_value.deleter
    def protected_value(self):
        raise AttributeError("do not delete, protected_value can be set to 0")

(注意，__init__指的是self。但属性方法引用self._protected_value。这样，__init__就可以通过公共API使用该属性，确保它是“受保护的”。)

和用法:

>>> p1 = Protective(3)
>>> p1.protected_value
3
>>> p1 = Protective(5.0)
>>> p1.protected_value
5
>>> p2 = Protective(-5)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in __init__
  File "<stdin>", line 15, in protected_value
ValueError: protectected_value must be between 0 and 100 inclusive
>>> p1.protected_value = 7.3
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 17, in protected_value
TypeError: protected_value must be an integer
>>> p1.protected_value = 101
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 15, in protected_value
ValueError: protectected_value must be between 0 and 100 inclusive
>>> del p1.protected_value
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 18, in protected_value
AttributeError: do not delete, protected_value can be set to 0

名字重要吗?

是的。setter和。deleter会复制原始属性。这允许子类在不改变父类中的行为的情况下正确地修改行为。

class Obj:
    """property demo"""
    #
    @property
    def get_only(self):
        return self._attribute
    #
    @get_only.setter
    def get_or_set(self, value):
        self._attribute = value
    #
    @get_or_set.deleter
    def get_set_or_delete(self):
        del self._attribute

现在为了让它工作，你必须使用各自的名称:

obj = Obj()
# obj.get_only = 'value' # would error
obj.get_or_set = 'value'  
obj.get_set_or_delete = 'new value'
the_value = obj.get_only
del obj.get_set_or_delete
# del obj.get_or_set # would error

我不确定这在什么情况下有用，但用例是如果您想要一个get、set和/或delete-only属性。可能最好是使用语义上相同的属性和相同的名称。

结论

从简单的属性开始。

如果以后需要设置、获取和删除相关的功能，可以使用属性装饰器添加它。

避免使用名为set_…和get_……-这就是属性的作用。

这是一个老问题，但这个话题非常重要，而且一直是最新的。如果有人想超越简单的getter /setter，我已经写了一篇关于python中超级属性的文章，支持插槽，可观察性和简化的样板代码。

from objects import properties, self_properties


class Car:
    with properties(locals(), 'meta') as meta:

        @meta.prop(read_only=True)
        def brand(self) -> str:
            """Brand"""

        @meta.prop(read_only=True)
        def max_speed(self) -> float:
            """Maximum car speed"""

        @meta.prop(listener='_on_acceleration')
        def speed(self) -> float:
            """Speed of the car"""
            return 0  # Default stopped

        @meta.prop(listener='_on_off_listener')
        def on(self) -> bool:
            """Engine state"""
            return False

    def __init__(self, brand: str, max_speed: float = 200):
        self_properties(self, locals())

    def _on_off_listener(self, prop, old, on):
        if on:
            print(f"{self.brand} Turned on, Runnnnnn")
        else:
            self._speed = 0
            print(f"{self.brand} Turned off.")

    def _on_acceleration(self, prop, old, speed):
        if self.on:
            if speed > self.max_speed:
                print(f"{self.brand} {speed}km/h Bang! Engine exploded!")
                self.on = False
            else:
                print(f"{self.brand} New speed: {speed}km/h")
        else:
            print(f"{self.brand} Car is off, no speed change")

这个类可以这样使用:

mycar = Car('Ford')

# Car is turned off
for speed in range(0, 300, 50):
    mycar.speed = speed

# Car is turned on
mycar.on = True
for speed in range(0, 350, 50):
    mycar.speed = speed

这段代码将产生以下输出:

Ford Car is off, no speed change
Ford Car is off, no speed change
Ford Car is off, no speed change
Ford Car is off, no speed change
Ford Car is off, no speed change
Ford Car is off, no speed change
Ford Turned on, Runnnnnn
Ford New speed: 0km/h
Ford New speed: 50km/h
Ford New speed: 100km/h
Ford New speed: 150km/h
Ford New speed: 200km/h
Ford 250km/h Bang! Engine exploded!
Ford Turned off.
Ford Car is off, no speed change

更多关于如何和为什么的信息，请访问:https://mnesarco.github.io/blog/2020/07/23/python-metaprogramming-properties-on-steroids

属性非常有用，因为你可以在赋值时使用它们，但也可以包括验证。你可以看到这段代码使用了装饰器@property和@<property_name>。Setter来创建方法:

# Python program displaying the use of @property 
class AgeSet:
    def __init__(self):
        self._age = 0

    # using property decorator a getter function
    @property
    def age(self):
        print("getter method called")
        return self._age

    # a setter function
    @age.setter
    def age(self, a):
        if(a < 18):
            raise ValueError("Sorry your age is below eligibility criteria")
        print("setter method called")
        self._age = a

pkj = AgeSet()

pkj.age = int(input("set the age using setter: "))

print(pkj.age)

在我写的这篇文章中也有更多的细节:https://pythonhowtoprogram.com/how-to-create-getter-setter-class-properties-in-python-3/

试试这个:Python属性

示例代码如下:

class C(object):
    def __init__(self):
        self._x = None

    @property
    def x(self):
        """I'm the 'x' property."""
        print("getter of x called")
        return self._x

    @x.setter
    def x(self, value):
        print("setter of x called")
        self._x = value

    @x.deleter
    def x(self):
        print("deleter of x called")
        del self._x


c = C()
c.x = 'foo'  # setter called
foo = c.x    # getter called
del c.x      # deleter called

使用@property和@attribute。Setter不仅可以帮助您使用“pythonic”方式，还可以在创建对象和更改对象时检查属性的有效性。

class Person(object):
    def __init__(self, p_name=None):
        self.name = p_name

    @property
    def name(self):
        return self._name

    @name.setter
    def name(self, new_name):
        if type(new_name) == str: #type checking for name property
            self._name = new_name
        else:
            raise Exception("Invalid value for name")

通过这种方式，您实际上可以向客户端开发人员“隐藏”_name属性，并对name属性类型进行检查。请注意，即使在初始化过程中也会调用setter。所以:

p = Person(12)

会导致:

Exception: Invalid value for name

But:

>>>p = person('Mike')
>>>print(p.name)
Mike
>>>p.name = 'George'
>>>print(p.name)
George
>>>p.name = 2.3 # Causes an exception