Issue 33197: Confusing error message when constructing invalid inspect.Parameters

Python 3.6.4

    In [15]: inspect.Parameter("foo", kind=inspect.Parameter.VAR_KEYWORD, default=42)
    ---------------------------------------------------------------------------
    ValueError                                Traceback (most recent call last)
    <ipython-input-15-7ed8c4fd15f3> in <module>()
    ----> 1 inspect.Parameter("foo", kind=inspect.Parameter.VAR_KEYWORD, default=42)

    /usr/lib/python3.6/inspect.py in __init__(self, name, kind, default, annotation)
    2442             if kind in (_VAR_POSITIONAL, _VAR_KEYWORD):
    2443                 msg = '{} parameters cannot have default values'.format(kind)
    -> 2444                 raise ValueError(msg)
    2445         self._default = default
    2446         self._annotation = annotation

    ValueError: 4 parameters cannot have default values

Note the "interesting" error message that starts with "4 parameters ..." (yes, I guess that inspect.Parameter == 4 internally...).

Probably just a matter of making the error f'{kind.name} parameters ...'.

@Antony Lee since you know the fix, do you want to submit a PR?

Also, _ParameterKind class has a __str__ method. So, I guess it's better to use "{!s}" in the format string instead of using kind.name.

@Nitish

I will take a look this issue.
I agree with to use "{!s}" in the format string

Can I get a code review for PR 6636?

PR 6636 is ready to be merged :)

New changeset a9cab433bbf02f3a1de59d14dc8f583181ffe2d5 by Yury Selivanov (Dong-hee Na) in branch 'master':
bpo-33197: Update a error message of invalid inspect.Parameters. (GH-6636)
https://github.com/python/cpython/commit/a9cab433bbf02f3a1de59d14dc8f583181ffe2d5

New changeset cb055bcc2bbfa5dcc6b0332305918a2118d9ebbc by Yury Selivanov (Miss Islington (bot)) in branch '3.7':
bpo-33197: Update a error message of invalid inspect.Parameters. (GH-6636) (GH-7204)
https://github.com/python/cpython/commit/cb055bcc2bbfa5dcc6b0332305918a2118d9ebbc

New changeset 5e9e9db9d9b648d2326e2853dc07377e12498e3f by Yury Selivanov (Miss Islington (bot)) in branch '3.6':
bpo-33197: Update a error message of invalid inspect.Parameters. (GH-6636) (#7205)
https://github.com/python/cpython/commit/5e9e9db9d9b648d2326e2853dc07377e12498e3f

@yselivanov

Please take a look PR 7206 :)

New changeset 4aa3006619392438b0775a2f488bbe9e7a22c468 by Yury Selivanov (Dong-hee Na) in branch 'master':
bpo-33197: Add description property for _ParameterKind. (GH-7206)
https://github.com/python/cpython/commit/4aa3006619392438b0775a2f488bbe9e7a22c468

Thanks!

We forgot to add "versionadded: 3.8" tag to the documentation of ParameterKind.description.  Dong-hee Na, could you please make a PR to add it?

Sure, I will send a PR soon.

@yselivanov

Please take a look PR 7536 :) Thanks!

> @yselivanov
> Please take a look PR 7536 :) Thanks!

Please stop posting comments like this frequently. They are highly distractive.

New changeset 4f54867e29af93779922ff23df542f2d5df4c4ee by Yury Selivanov (Dong-hee Na) in branch 'master':
bpo-33197: Add versionadded tag to the documentation of ParameterKind (GH-7536)
https://github.com/python/cpython/commit/4f54867e29af93779922ff23df542f2d5df4c4ee

messages: + msg319060

stage: patch review -> resolved

type: behavior
versions: + Python 3.7, Python 3.8