[issue24205] signature.bind error messages are sub-optimal
Yury Selivanov added the comment: Hi David, Please see the attached patch. It doesn't make Signature.bind() exceptions look exactly like system messages, but it's now much closer. -- keywords: +patch Added file: http://bugs.python.org/file39422/sig_exc.patch ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24205 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24205] signature.bind error messages are sub-optimal
Changes by Yury Selivanov yseliva...@gmail.com: -- assignee: - yselivanov ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24205 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24205] signature.bind error messages are sub-optimal
Martin Panter added the comment: I think the patch is okay. Just beware that next(iter(kwargs)) can return different names if there is more than one unexpected argument, so the error message could vary. But it looks like the test cases are only when there is exactly one extra argument, so no problem. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24205 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24205] signature.bind error messages are sub-optimal
Roundup Robot added the comment: New changeset 3cc368d334c5 by Yury Selivanov in branch 'default': Issue 24205: Improve inspect.Signature.bind() error messages. https://hg.python.org/cpython/rev/3cc368d334c5 -- nosy: +python-dev ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24205 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24205] signature.bind error messages are sub-optimal
Changes by Yury Selivanov yseliva...@gmail.com: -- resolution: - fixed stage: - resolved status: open - closed ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24205 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24205] signature.bind error messages are sub-optimal
Changes by Martin Panter vadmium...@gmail.com: -- nosy: +vadmium ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24205 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24205] signature.bind error messages are sub-optimal
Changes by Ethan Furman et...@stoneleaf.us: -- nosy: +ethan.furman ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24205 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24205] signature.bind error messages are sub-optimal
New submission from R. David Murray:
I have an application where I'm calling a handler function with passed in
arguments. I want to generate an error if the handler is called with the wrong
arguments. I can't just catch TypeError since a TypeError could easily result
from some programming error in the handler, rather than an error in the calling
args. So, doing this seems obvious:
sig = signature(handler)
try:
bound = sig.bind(message, payload, *args, **kw)
except TypeError as exc:
print(Invalid handler call: {}.format(str(exc))
handler(*bound.args, **bound.kwargs)
Now, suppose I have a function like:
def foo(message, payload, anarg, akeyword='bar'):
pass
If I call it directly with an invalid keyword argument I get:
foo(1, 2, 3, badword=7)
Traceback (most recent call last):
File stdin, line 1, in module
TypeError: foo() got an unexpected keyword argument 'badword'
However, bind gives me:
sig.bind(1, 2, 3, badword=7)
Traceback (most recent call last):
File stdin, line 1, in module
File /home/rdmurray/python/p35/Lib/inspect.py, line 2818, in bind
return args[0]._bind(args[1:], kwargs)
File /home/rdmurray/python/p35/Lib/inspect.py, line 2809, in _bind
raise TypeError('too many keyword arguments')
TypeError: too many keyword arguments
Similarly, for a missing argument I get:
foo(1, 2)
Traceback (most recent call last):
File stdin, line 1, in module
TypeError: foo() missing 1 required positional argument: 'anarg'
While bind gives:
sig.bind(1, 2)
Traceback (most recent call last):
File stdin, line 1, in module
File /home/rdmurray/python/p35/Lib/inspect.py, line 2818, in bind
return args[0]._bind(args[1:], kwargs)
File /home/rdmurray/python/p35/Lib/inspect.py, line 2737, in _bind
raise TypeError(msg) from None
TypeError: 'anarg' parameter lacking default value
So, using this to replace catching the TypeError from incorrectly calling a
function does not work. Nor are the messages in fact accurate. Is there any
chance we could make bind's error handling work like regular function binding?
That's certainly what I expected would happen!
--
components: Library (Lib)
messages: 243287
nosy: r.david.murray, yselivanov
priority: normal
severity: normal
status: open
title: signature.bind error messages are sub-optimal
type: behavior
versions: Python 3.5
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