`__set_name__` not called on class construction for `wrapt.decorator`-wrapped descriptors

wrapt version: 1.12.1

---

I was using wrapt.decorator in combination with descriptors. However, I found that __set_name__ was not called on the descriptor when it’s being decorated:

import wrapt


@wrapt.decorator
def decorator(wrapped, instance, args, kwargs):
    return wrapped(*args, **kwargs)


class descriptor_wrapper:
    def __init__(self, descriptor):
        self.__wrapped__ = descriptor

    def __set_name__(self, owner, name):
        print("__set_name__", self, owner, name)
        if hasattr(self.__wrapped__, "__set_name__"):
            self.__wrapped__.__set_name__(owner, name)

    def __get__(self, instance, owner=None):
        print("__get__", self, instance, owner)
        return self.__wrapped__.__get__(instance, owner)


class MyClass:
    @descriptor_wrapper
    def this_works(self):
        pass

    @decorator
    @descriptor_wrapper
    def this_doesnt_work(self):
        pass

The output is:

__set_name__ <__main__.descriptor_wrapper object at 0x7f66360bac40> <class '__main__.MyClass'> this_works

But it is expected that __set_name__ be called for both descriptors.

On the other hand, lookup on the decorated descriptor seems to work:

>>> hasattr(MyClass.__dict__["this_doesnt_work"], "__set_name__")
True
>>> MyClass.__dict__["this_doesnt_work"].__set_name__(MyClass, "this_doesnt_work")
__set_name__ <__main__.descriptor_wrapper object at 0x7f66360baa00> <class '__main__.MyClass'> this_doesnt_work

but it just doesn’t get called during class construction.

[GrahamDumpleton]

The __set_name__ support when using wrapt.decorator is included in 1.13.0.

BTW, if interested in playing with pickling further and want an easy way of overriding the builtin FunctionWrapper to add the pickle methods, in 1.13.0 you can do:

class MyBoundFunctionWrapper(wrapt.BoundFunctionWrapper):
    pass

class MyFunctionWrapper(wrapt.FunctionWrapper):
    __bound_function_wrapper__ = MyBoundFunctionWrapper

@wrapt.decorator(proxy=MyFunctionWrapper)
def wrapper(wrapped, instance, args, kwargs):
    return wrapped(args, kwargs)

Version 1.13.0 is available on PyPi at the moment as release candidates.

• https://pypi.org/project/wrapt/#history

Anyway, going to close out this issue at this point.

[GrahamDumpleton]

Have made changes to add __set_name__() propagation to FunctionWrapper, but not ObjectProxy.

• https://github.com/GrahamDumpleton/wrapt/blob/develop/docs/changes.rst

You can try develop branch if you want to verify it works for you.

pip install -U https://github.com/GrahamDumpleton/wrapt/archive/refs/heads/develop.zip