more argument error improving

[benjaminp]

BPO	12356
Nosy	@ncoghlan, @benjaminp
Files	argerror.patch

^{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 = <Date 2011-06-24.14:37:39.562>
created_at = <Date 2011-06-18.00:45:31.191>
labels = ['interpreter-core', 'type-feature']
title = 'more argument error improving'
updated_at = <Date 2011-06-24.14:37:39.561>
user = 'https://github.com/benjaminp'

bugs.python.org fields:

activity = <Date 2011-06-24.14:37:39.561>
actor = 'python-dev'
assignee = 'none'
closed = True
closed_date = <Date 2011-06-24.14:37:39.562>
closer = 'python-dev'
components = ['Interpreter Core']
creation = <Date 2011-06-18.00:45:31.191>
creator = 'benjamin.peterson'
dependencies = []
files = ['22399']
hgrepos = []
issue_num = 12356
keywords = ['patch']
message_count = 4.0
messages = ['138563', '138868', '138887', '138950']
nosy_count = 3.0
nosy_names = ['ncoghlan', 'benjamin.peterson', 'python-dev']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue12356'
versions = ['Python 3.3']

[benjaminp]

After completing bpo-12265, it was pointed out to me that the error message is still not perfect:

>>> def f(a, b, c=3, d=4, e=6, f=3, g=32): pass
... 
>>> f(1, f=4, d=90)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f() takes from 2 to 7 positional arguments but 3 were given

Here is a new patch.

Some samples:

>>> def f(a): pass
... 
>>> f()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f() missing 1 required positional argument: 'a'
>>> def f(a, b): pass
... 
>>> f()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f() missing 2 required positional arguments: 'a' and 'b'

>>> def f(a, b, c): pass
... 
>>> f()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f() missing 3 required positional arguments: 'a', 'b', and 'c
>>> def f(a, b, c, d): pass
>>> f()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f() missing 4 required positional arguments: 'a', 'b', 'c', and 'd'

Same with kwonly:

>>> def f(*, w): pass
... 
>>> f()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f() missing 1 required keyword-only argument: 'w'
>>> def f(*, a, b, c, d, e): pass
... 
>>> f()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f() missing 5 required keyword-only arguments: 'a', 'b', 'c', 'd', and 'e'

For too many positional arguments, the old (new) error is retained:

>>> def f(a): pass
... 
>>> f(1, 2, 3)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f() takes 1 positional argument but 3 were given
>>> f(3, 4, 5)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f() takes from 1 to 2 positional arguments but 3 were given

[benjaminp]

Nick (or anyone else), do you want to look at this?

[ncoghlan]

Revised error messages and tests look reasonable and the code seems fine on a visual scan.

+1 from me.

[python-dev]

New changeset 52744a5a9260 by Benjamin Peterson in branch 'default':
give the names of missing positional or keyword-only arguments (closes bpo-12356)
http://hg.python.org/cpython/rev/52744a5a9260