1.__getattr__ 和 __getattribute__区别
1.
__getattr__在访问对象的属性而属性不存在时触发。它只会在属性不存在时调用，而对已存在的属性访问不会触发。2.
__getattribute__在访问对象的任何属性时都会触发。无论属性是否存在，每次属性访问都会经过__getattribute__。
1.1使用__getattribute__
class A:
def __init__(self, x) -> None:
self.x = x
def __getattr__(self, name):
print('__getattr__')
def __getattribute__(self, __name: str):
print('__getattribute__')
print(__name)
return 222
a = A(1)
print(a.a)
print(a.z)
__getattribute__
a
222
__getattribute__
z
222
1.2使用__getattr__
from builtins import AttributeError
class A:
def __init__(self, x) -> None:
self.x = x
def __getattr__(self, name):
print('__getattr__')
def __getattribute__(self, __name: str):
print('__getattribute__')
print(__name)
AttributeError('not find')
a = A(1)
print(a.x)
print(a.z)
__getattribute__
x
None
__getattribute__
z
None
1.3用法
当使用
obj.undefined_attr时，如果__getattribute__存在，它会首先被调用。只有在__getattribute__中抛出AttributeError异常时，__getattr__才会被调用。如果
__getattribute__不存在，或者它没有引发AttributeError异常，__getattr__不会被调用。
class A:
def __init__(self, x) -> None:
self.x = x
def __getattr__(self, name):
print('__getattr__')
def __getattribute__(self, __name: str):
print('__getattribute__')
return object.__getattribute__(self, __name)
a = A(1)
print(a.x)
print(a.z)
__getattribute__
1
__getattribute__
__getattr__
None