Type signature of @property not shown in help()

[McSinyx]

BPO	39125
Nosy	@rhettinger, @McSinyx, @tirkarthi

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-12-23.15:40:00.651>
labels = ['type-feature', '3.9', 'docs']
title = 'Type signature of @property not shown in help()'
updated_at = <Date 2021-04-11.00:19:47.157>
user = 'https://github.com/McSinyx'

bugs.python.org fields:

activity = <Date 2021-04-11.00:19:47.157>
actor = 'rhettinger'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2019-12-23.15:40:00.651>
creator = 'McSinyx'
dependencies = []
files = []
hgrepos = []
issue_num = 39125
keywords = []
message_count = 5.0
messages = ['358823', '358825', '359041', '390625', '390754']
nosy_count = 5.0
nosy_names = ['rhettinger', 'docs@python', 'McSinyx', 'xtreak', 'brenthuisman']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue39125'
versions = ['Python 3.9']

[McSinyx]

Dear Maintainer,

I want to request a feature on the generative documentation of type-hinting.
As of December 2019, I believe there is no support for generating such
information in help(). For demonstration, I have this tiny piece of code

class Foo:
    @property
    def bar(self) -> int: return 42

    @bar.setter
    def bar(self, value: int) -> None: pass

    def baz(self, arg: float) -> str: pass

whose documentation on CPython 3.7.5 (on Debian testing amd64 if that matters)
is generated as

class Foo(builtins.object)
 |  Methods defined here:
 |  
 |  baz(self, arg: float) -> str
 |  
 |  

---

| Data descriptors defined here:
|
| __dict__
| dictionary for instance variables (if defined)
|
| __weakref__
| list of weak references to the object (if defined)
|
| bar

I expect the documentation for bar to be as informative as bar, i.e. something
similar to ``bar: int''. As pointed out by ChrisWarrick on freenode#python,
the annotations are already present, yet help() is not making use of them:

>>> Foo.bar.fget.__annotations__
{'return': <class 'int'>}
>>> Foo.bar.fset.__annotations__
{'value': <class 'int'>, 'return': None}

Have a Merry Christmas or other holiday of your choice,
Nguyễn Gia Phong

[tirkarthi]

Currently docstring written for even property.setter is ignored in help as inspect.getdoc only inspects property.fget [0] for docstrings. I feel docs for setter could also be included. The docs also indicate the same at https://docs.python.org/3.6/library/functions.html#property . In the absence of docs maybe the signature for getter and setter could be included as per this proposal.

class Foo:
    @property
    def bar(self) -> int:
        '''Bar docs for property'''
        return 42

    @bar.setter
    def bar(self, value: int) -> None:
        '''Bar docs for setter'''
        pass

help(Foo.bar)

Help on property:

Bar docs for property

[0]

cpython/Lib/inspect.py

Line 580 in 4b3b122

elif isinstance(obj, property):