e贱人就是矫情
问题描述
Python 为我们提供了很多关于实例/类属性的可能性，例如:
Python provides us many possibilities on instance/class attribute, for example:
class A(object):
def __init__(self):
self.foo = "hello"
a = A()
有很多方法可以访问/更改self.foo的值:
There are many ways to access/change the value of self.foo:
- 直接访问a.foo
- 内部字典 a.__dict__['foo']
- 获取和设置a.__get__和a.__set__，当然还有两个预定义的方法.
- getattribute a.__getattribute__
- __getattr__ 和 __setattr__
- 也许更多.
- direct access a.foo
- inner dict a.__dict__['foo']
- get and set a.__get__ and a.__set__,of course there two are pre-defined methods.
- getattribute a.__getattribute__
- __getattr__ and __setattr__
- maybe more.
在阅读源代码时，我总是不知道它们的最终访问顺序是什么?当我使用 a.foo 时，我怎么知道哪个方法/属性会被实际调用?
While reading source code, I always get lost of what's their ultimate access order? When I use a.foo, how do I know which method/attribute will get called actually?
推荐答案
bar = a.foo...
- 调用 a.__getattribute__('foo')
- 默认情况下会查找 a.__dict__['foo']
- 如果在 A 上定义，则调用 foo 的 .__get__().
- invokes a.__getattribute__('foo')
- which in turn by default looks up a.__dict__['foo']
- or invokes foo's .__get__() if defined on A.
然后将返回的值分配给 bar.
The returned value would then be assigned to bar.
a.foo = bar...
- 调用 a.__getattribute__('foo')
- 默认情况下会查找 a.__dict__['foo']
- 如果在 A 上定义，则调用 foo 的 .__set__(bar).
