Set Process.info to None by default

[sobolevn]

Refs python/typeshed#10195

Summary

• OS: any
• Bug fix: yes
• Type: core
• Fixes: None

Description

Right now .info attribute is only set during process_iter, which is not quite correct.
This results in AttributeError when using regular Process:

>>> import psutil
>>> psutil.Process(1)
psutil.Process(pid=1, name='launchd', status='running', started='2023-05-27 09:31:50')
>>> psutil.Process(1).info
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Process' object has no attribute 'info'

I propose using None default for cases when it is not created using process_iter.

This way it will simplify typing of Process for us.

[giampaolo]

Hmm... debatable.
I think I'm more keen on agreeing with you: I suppose it's less surprising for the user if info attribute is always set. I wonder if it's more correct for it to be an empty dict {} rather than None though. Uhmm...

[sobolevn]

Oh, whatever you like, I am not a user of this feature, so I cannot really decide.

[emcek]

Hmm... debatable. I think I'm more keen on agreeing with you: I suppose it's less surprising for the user if info attribute is always set. I wonder if it's more correct for it to be an empty dict {} rather than None though. Uhmm...

Yes, I think empty dict is fine!

[ringohoffman]

I came here to raise a similar issue. This example from the docs raises type errors since info is not defined in the __init__:

https://psutil.readthedocs.io/en/latest/#psutil.process_iter:

import psutil
for proc in psutil.process_iter(['pid', 'name', 'username']):
    print(proc.info)  # Cannot access member "info" for type "Process"; Member "info" is unknown

We would need to update the type stubs accordingly: https://github.com/python/typeshed/blob/e347af1d59ed46478a788ed60fd02096fce26edd/stubs/psutil/psutil/__init__.pyi#L158

[sobolevn]

Oh, closing in favor of #2267
Sorry, I haven't seen your PR! 👍