Description

assignee = None
closed_at = None
created_at = <Date 2021-01-29.21:00:52.553>
labels = ['type-feature', 'library', '3.10']
title = 'inspect.signature(bytes.hex) raises ValueError "builtin has invalid signature"'
updated_at = <Date 2021-01-29.21:00:52.553>
user = 'https://github.com/verhovsky'

activity = <Date 2021-01-29.21:00:52.553>
actor = 'boris'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-01-29.21:00:52.553>
creator = 'boris'
dependencies = []
files = []
hgrepos = []
issue_num = 43067
keywords = []
message_count = 1.0
messages = ['385940']
nosy_count = 1.0
nosy_names = ['boris']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue43067'
versions = ['Python 3.10']

Activity

1. verhovsky commented on Jan 29, 2021

   

   verhovskymannequin

   on Jan 29, 2021

   MannequinAuthor

   More actions

   On Python 3.9

   >>> import inspect
   >>> inspect.signature(bytes.hex)
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
     File "/usr/lib/python3.9/inspect.py", line 3118, in signature
       return Signature.from_callable(obj, follow_wrapped=follow_wrapped)
     File "/usr/lib/python3.9/inspect.py", line 2867, in from_callable
       return _signature_from_callable(obj, sigcls=cls,
     File "/usr/lib/python3.9/inspect.py", line 2322, in _signature_from_callable
       return _signature_from_builtin(sigcls, obj,
     File "/usr/lib/python3.9/inspect.py", line 2135, in _signature_from_builtin
       return _signature_fromstr(cls, func, s, skip_bound_arg)
     File "/usr/lib/python3.9/inspect.py", line 2005, in _signature_fromstr
       raise ValueError("{!r} builtin has invalid signature".format(obj))
   ValueError: <method 'hex' of 'bytes' objects> builtin has invalid signature

   This is also true for memoryview.hex and bytearray.hex . This happens because

   >>> bytes.hex.__text_signature__
   '($self, /, sep=<unrepresentable>, bytes_per_sep=1)'

   when it would make more sense for it to return

   '($self, /, sep='', bytes_per_sep=1)'

   or at least sep=None
2. verhovsky

   added

   3.10 (EOL)end of lifeend of life

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   type-featureA feature request or enhancementA feature request or enhancement

   on Jan 29, 2021
3. ezio-melotti

   transferred this issue fromon Apr 10, 2022
4. JelleZijlstra commented on Nov 9, 2023

   

   JelleZijlstra

   on Nov 9, 2023

   Member

   More actions

   I am looking at this because I realized it's preventing us from testing some signatures in typeshed.

   I got this to work:

   >>> import inspect
   >>> inspect.signature(bytes.hex)
   <Signature (self, /, sep=Ellipsis, bytes_per_sep=1)>
   

   But it feels wrong to claim Ellipsis as the default, because that's not really true. A more principled solution would be to add a Parameter.unrepresentable marker and use that as the default, but that feels like a change we can make only in 3.13, not in the bugfix branches.

   My leaning is to apply the fix suggested above in 3.13, and put some hack in stubtest (or other tools that want to inspect signatures) to make it work on earlier versions.
5. JelleZijlstra commented on Nov 9, 2023

   

   JelleZijlstra

   on Nov 9, 2023

   Member

   More actions

   This is basically @sobolevn's idea from https://discuss.python.org/t/ac-null-defaults-prevent-correct-signatures-lets-add-inspect-unrepresentable-to-fix-this/30753/6.
6. sobolevn commented on Nov 9, 2023

   

   sobolevn

   on Nov 9, 2023

   Member

   More actions

   @serhiy-storchaka said that future inspect.signatures() is a better solution. But, it is in the works.
7. JelleZijlstra

   added a commit that references this issue on Nov 9, 2023

   stubtest: hack for "<unrepresentable>" defaults

   3e2ca6f
8. JelleZijlstra

   added a commit that references this issue on Nov 18, 2023

   stubtest: hack for "<unrepresentable>" defaults (#16433)

   706389d
9. serhiy-storchaka

   added this to Inspect issues 🔍on Mar 5, 2024

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