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PEP 3102 and PEP 570 should say **Keyword-Only Parameters** instead of **Keyword-Only Arguments** #133438
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PEPs are historical documents that won't get updates like that and thus they may contain typos or errors. We don't have a policy of publishing erratas though (@AA-Turner maybe it'd be good to have an errata policy?)
Is there anywhere that the error appears in the current documentation? As Ben says, as a
rule we don't tend to update Final PEPs.A
All occurrences in Cpython:
Modules/_testcapi/getargs.c:/* test PyArg_ParseTupleAndKeywords keyword-only arguments */ Doc/c-api/arg.rst: keyword-only. Currently, all keyword-only arguments must also be optional Doc/whatsnew/3.0.rst:* :pep:`3102`: Keyword-only arguments. Named parameters occurring Doc/whatsnew/3.0.rst: argument list, but you do have keyword-only arguments. Doc/whatsnew/3.4.rst:keyword-only arguments. It also provides some efficiency improvements. Doc/whatsnew/3.4.rst:* Defaults for keyword-only arguments are now evaluated *after* defaults for Doc/library/unittest.mock.rst: Added two keyword-only arguments to the reset_mock function. Doc/library/exceptions.rst: The optional *name* and *path* keyword-only arguments Doc/library/functions.rst: There are two optional keyword-only arguments. The *key* argument specifies Doc/library/functions.rst: There are two optional keyword-only arguments. The *key* argument specifies Doc/library/inspect.rst: Example: print all keyword-only arguments without default values: Doc/library/collections.rst: :ref:`keyword-only arguments <keyword-only_parameter>`. Doc/library/stdtypes.rst: (:ref:`keyword-only arguments <keyword-only_parameter>`): Doc/library/ast.rst: * ``kw_defaults`` is a list of default values for keyword-only arguments. If Doc/library/pickle.rst: class requires keyword-only arguments. Otherwise, it is recommended for Doc/library/subprocess.rst: be set by passing them as keyword-only arguments. Doc/tutorial/controlflow.rst:Keyword-Only Arguments Misc/HISTORY: missing keyword-only arguments. Patch by Jeremiah Lowin. Misc/HISTORY:- Issue #20619: Give the AST nodes of keyword-only arguments a column and line Misc/HISTORY:- Issue #14607: Fix keyword-only arguments which started with ``__``. Misc/HISTORY:- Issue #12356: When required positional or keyword-only arguments are not Misc/HISTORY:- PEP 3102: keyword-only arguments. Misc/NEWS.d/3.5.0a3.rst:of instances of classes whose __new__ method takes keyword-only arguments. Misc/NEWS.d/3.12.0a1.rst:missing keyword-only arguments. Misc/NEWS.d/3.10.0b1.rst:will become keyword-only arguments to the generated __init__. Misc/NEWS.d/3.5.0a1.rst:keyword-only arguments. Patch by Jeremiah Lowin. Lib/_ast_unparse.py: # varargs, or bare '*' if no varargs but keyword-only arguments present Lib/_ast_unparse.py: # keyword-only arguments Lib/pydoc_data/topics.py: keyword (keyword-only arguments): Lib/test/test_positional_only_arg.py: with self.assertRaisesRegex(TypeError, r"missing 2 required keyword-only arguments: 'd' and 'e'"): Lib/test/test_positional_only_arg.py: r"\(and 2 keyword-only arguments\) were given"): Lib/test/test_extcall.py: TypeError: f() takes 0 positional arguments but 3 positional arguments (and 2 keyword-only arguments) were given Lib/test/test_extcall.py: TypeError: f() missing 5 required keyword-only arguments: 'a', 'b', 'c', 'd', and 'e' Lib/test/test_keywordonlyarg.py: # more than 255 keyword-only arguments, should compile ok Lib/inspect.py: 'args' is the list of argument names. Keyword-only arguments are Lib/inspect.py: # keyword-only arguments Lib/inspect.py: Parameter objects (keyword-only arguments are in the same order Lib/inspect.py: # a '*' to separate keyword-only arguments Lib/copyreg.py: keyword-only arguments to be pickled correctly. Python/ast_unparse.c: /* vararg, or bare '*' if no varargs but keyword-only arguments present */ Python/ast_unparse.c: /* keyword-only arguments */There are some that should be fixed.
I think we should generally continue the policy of leaving PEPs as historical docs. In particular, I don't think this issue should be an exception. So either 1) this issue should be closed and a new one opened, with Stan's list copied over; or 2) the title and initial comment should be revised (but then following comments, including this, would not fit). I suggest 1).
For the revised or new issue: in some cases, '-only' should be removed, resulting in 'keyword argument'; in others, s/argument/parameter, as proposed.
Reacted by Serhiy Storchaka- the title and initial comment should be revised (but then following comments, including this, would not fit). I suggest 1).
IMO either is fine as for 2), the comments can be marked as "resolved" (or similar) hiding them.
There are many other cases of misusing "argument" and "parameter".
#135160 fixes the use of the terms "argument" and "parameter" in the documentation. A following PR will fix also error messages and output.
FWIW, I'd keep the phrase keyword-only argument in (most) places where we're really talking about arguments, like “This function accepts a keyword-only foo argument.”
Theonlyis redundant, but it makes it clearer that you can't pass the value positionally.I'm closing this issue:
- PEPs generally are not changed after they are accepted
- If we were to change a PEP, we'd do it in https://github.com/python/peps, not this repo
- The distinction between arguments and parameters is mostly pedantic, and sometimes depends on your perspective
- Litigating every "argument" and "parameter" to decide which is right is a lot of work with little benefit. See gh-133438: Fix the use of the terms "argument" and "parameter" in the documentation #135160 for discussion of this.
PEP 3102 and PEP 570 say Keyword-Only Arguments but they should say Keyword-Only Parameters because a keyword-only parameter is the parameter which only accepts a keyword argument.
Actually, PEP 570 correctly says Positional-Only Parameters because a positional-only parameter is the parameter which only accepts a positional argument.
Glossary explains a keyword argument and positional argument.
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