Luofeiyu, you are asking very advanced questions. How experienced with
Python are you? Asking about __get__ is nearly never needed. __get__ is
used internally by built-ins like property, classmethod and staticmethod.
99.99% of Python programmers will never need to write a __get__ method, and
of the 0.01% who do, they might only write one or two in their whole
career.
luofeiyu wrote:
> class C(object):
> a = 'abc'
> def __getattribute__(self, *args, **kwargs):
> print("__getattribute__() is called")
> return object.__getattribute__(self, *args, **kwargs)
> def __getattr__(self, name):
> print("__getattr__() is called ")
> return name + " from getattr"
> def __get__(self, instance, owner):
> print("__get__() is called", instance, owner)
> return self
> def foo(self, x):
> print(x)
[...]
> If call an attribute which does exist ,__getattribute__() is called
> If call an attribute which does not exist ,__getattribute__() is called
> and then __getattr__() is called ?
Correct.
> when the __get__ method will be called?no chance for my example?
No chance for your example. __get__ is used in the "descriptor protocol",
used for methods and properties. You can see __get__ called here:
class D(object):
foo = C()
d = D()
d.foo
Now C.__get__ will be called.
--
Steven
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