[New-bugs-announce] [issue45356] Calling `help` executes @classmethod @property decorated methods

[Randolf Scholz]

New submission from Randolf Scholz <randolf.scholz at gmail.com>:

I noticed some strange behaviour when calling `help` on a class inheriting from a class or having itself @classmethod @property decorated methods.

```python
from time import sleep
from abc import ABC, ABCMeta, abstractmethod

class MyMetaClass(ABCMeta):
    @classmethod
    @property
    def expensive_metaclass_property(cls):
        """This may take a while to compute!"""
        print("computing metaclass property"); sleep(3)
        return "Phew, that was a lot of work!"

    
class MyBaseClass(ABC, metaclass=MyMetaClass):
    @classmethod
    @property
    def expensive_class_property(cls):
        """This may take a while to compute!"""
        print("computing class property .."); sleep(3)
        return "Phew, that was a lot of work!"
    
    @property
    def expensive_instance_property(self):
        """This may take a while to compute!"""
        print("computing instance property ..."); sleep(3)
        return "Phew, that was a lot of work!"

class MyClass(MyBaseClass):
    """Some subclass of MyBaseClass"""
    
help(MyClass)
```

Calling `help(MyClass)` will cause `expensive_class_property` to be executed 4 times (!)

The other two properties, `expensive_instance_property` and `expensive_metaclass_property` are not executed.

Secondly, only `expensive_instance_property` is listed as a read-only property; `expensive_class_property` is listed as a classmethod and `expensive_metaclass_property` is unlisted.

The problem is also present in '3.10.0rc2 (default, Sep 28 2021, 17:57:14) [GCC 10.2.1 20210110]'

Stack Overflow thread: https://stackoverflow.com/questions/69426309

----------
files: classmethod_property.py
messages: 403109
nosy: randolf.scholz
priority: normal
severity: normal
status: open
title: Calling `help` executes @classmethod @property decorated methods
type: behavior
versions: Python 3.10, Python 3.9
Added file: https://bugs.python.org/file50325/classmethod_property.py

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue45356>
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