[issue25810] Python 3 documentation for eval is incorrect
New submission from Andre Roberge: The documentation for eval() indicates that it takes keyword arguments: eval(expression, globals=None, locals=None) However, that is incorrect, as indicated by the builtin help:
help(eval) Help on built-in function eval in module builtins:
eval(...) eval(source[, globals[, locals]]) -> value ---------- assignee: docs@python components: Documentation messages: 255969 nosy: aroberge, docs@python priority: normal severity: normal status: open title: Python 3 documentation for eval is incorrect versions: Python 3.2, Python 3.3, Python 3.4, Python 3.5, Python 3.6 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
SilentGhost added the comment: I think this is the case where hard-coded strings where not updated in the C files. ---------- nosy: +SilentGhost versions: -Python 3.5, Python 3.6 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
Changes by SilentGhost <ghost.adh@gmail.com>: ---------- stage: -> needs patch _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
random832 added the comment: Whatever the case may be, it *doesn't* support keyword arguments. e.g.:
eval("a+b", globals={'a':1}, locals={'b':2}) TypeError: eval() takes no keyword arguments
So as the current situation stands, the documentation is wrong, and the help string is consistent with the code's actual behavior. Confirmed in Python 3.5.0. ---------- nosy: +random832 versions: +Python 3.5 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
random832 added the comment: Oh, I just noticed, the help string is also wrong in 3.5 (which explains why you removed 3.5 from the versions list, which I hadn't noticed until after posting my previous comment). ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
SilentGhost added the comment: Yes, whatever Andre's posted is not an output from 3.5. It's 3.4 or earlier. Also it's a wider problem because the same issue exists for exec: built-in help shows keyword arguments, while docs and implementation require only positional. ---------- versions: +Python 3.6 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
random832 added the comment: I guess the next question is what the intent is. Was there an intent, which was not followed through on, to upgrade these methods to support keyword arguments? Or is there an intent (here and everywhere) that documentation using keyword argument syntax is appropriate to use to document methods that have default values but do not in fact support keyword arguments? What does the "/" in the help text mean? According to PEP 0436 (Argument Clinic), the "/" here indicates that the preceding parameters are positional-only, despite the apparent use of keyword syntax. Should this convention also be used in the documentation? ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
SilentGhost added the comment: I'm not sure how the people are supposed to discover this convention according to pep 436. Or is this now intended as two separate incompatible conventions for online docs and built-in help? ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
Changes by SilentGhost <ghost.adh@gmail.com>: ---------- nosy: +larry _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
Martin Panter added the comment: See Issue 23738 where my current patch proposes using the PEP 457 slash (/) notation in the RST documentation, including for eval(). I’m not sure if there is a clear concensus for applying my patch however. An alternative would be to use the square-bracket notation, and explain in the text that the default values are None. See also Issue 21314 about explaining the slash notation used by Argument Clinic and pydoc. ---------- nosy: +martin.panter versions: -Python 3.2, Python 3.3 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
random832 added the comment: What about fixing all methods so that they can take keywords? Are the functions with their current C signatures part of the stable ABI? Is there somewhere we could centrally add some magic "convert tuple+keywords to tuple, given list of names" code? ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
Martin Panter added the comment: See Issue 8706 about changing functions and methods to accept keyword arguments. But this cannot be done in general. What would you call the first argument to dict() such that all possible keyword arguments still work? What is the first range() argument called: start or stop? ---------- _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
R. David Murray added the comment: As I recall it, in the python2 docs we used the [... notation, sometimes even when the actual arguments were or accepted keywords. In the python3 docs we converted to always using keyword notation...and then realized that that also caused confusion, in the other direction. Some things we converted back to [... notation. Then argument clinic came along, and we kind of postponed worrying about it until we converted as much as practical to argument clinic. I think we are moving toward using (and documenting in the main docs) the / notation. Especially since it shows up in the inspect module as well as the docstring help. Martin, if you don't think you have consensus on your patch, perhaps it is time to ping python-dev. ---------- nosy: +r.david.murray _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
Changes by Ezio Melotti <ezio.melotti@gmail.com>: ---------- nosy: +ezio.melotti type: -> enhancement versions: -Python 3.4 _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue25810> _______________________________________
Change by Berker Peksag <berker.peksag@gmail.com>: ---------- nosy: +berker.peksag _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue25810> _______________________________________
Cheryl Sabella <cheryl.sabella@gmail.com> added the comment: See also PEP570 and issue 36540. ---------- nosy: +cheryl.sabella _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue25810> _______________________________________
Change by Philipp Rauch <smokephil@gmail.com>: ---------- versions: +Python 3.7 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue25810> _______________________________________
Change by Philipp Rauch <smokephil@gmail.com>: ---------- versions: +Python 3.8, Python 3.9 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue25810> _______________________________________
Change by Roundup Robot <devnull@psf.upfronthosting.co.za>: ---------- keywords: +patch pull_requests: +14905 stage: needs patch -> patch review pull_request: https://github.com/python/cpython/pull/15173 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue25810> _______________________________________
Gregory P. Smith <greg@krypto.org> added the comment: New changeset 7a0023e8d17566eb32c836b65c33663303a2224f by Gregory P. Smith (smokephil) in branch 'master': bpo-25810: Clarify eval() docs, it does not keywords (GH-15173) https://github.com/python/cpython/commit/7a0023e8d17566eb32c836b65c33663303a... ---------- nosy: +gregory.p.smith _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue25810> _______________________________________
Change by miss-islington <mariatta.wijaya+miss-islington@gmail.com>: ---------- pull_requests: +15551 pull_request: https://github.com/python/cpython/pull/15910 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue25810> _______________________________________
Change by miss-islington <mariatta.wijaya+miss-islington@gmail.com>: ---------- pull_requests: +15552 pull_request: https://github.com/python/cpython/pull/15911 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue25810> _______________________________________
miss-islington <mariatta.wijaya+miss-islington@gmail.com> added the comment: New changeset 4e914ab29f6d48a9fd045ea6a25dbf9e2fb603f9 by Miss Islington (bot) in branch '3.8': bpo-25810: Clarify eval() docs, it does not keywords (GH-15173) https://github.com/python/cpython/commit/4e914ab29f6d48a9fd045ea6a25dbf9e2fb... ---------- nosy: +miss-islington _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue25810> _______________________________________
miss-islington <mariatta.wijaya+miss-islington@gmail.com> added the comment: New changeset d378fdb10a5476b86b5a01d74c1bcc4e2f52e003 by Miss Islington (bot) in branch '3.7': bpo-25810: Clarify eval() docs, it does not keywords (GH-15173) https://github.com/python/cpython/commit/d378fdb10a5476b86b5a01d74c1bcc4e2f5... ---------- _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue25810> _______________________________________
participants (12)
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Andre Roberge -
Berker Peksag
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Cheryl Sabella
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Ezio Melotti
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Gregory P. Smith
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Martin Panter
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miss-islington
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Philipp Rauch
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R. David Murray
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random832
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Roundup Robot
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SilentGhost