bpo-26680: Incorporate is_integer in all built-in and standard library numeric types#6121
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skrah commented Mar 26, 2019
This issue is probably languishing because of the amount of controversy it generated. Was there a pronouncement from Guido on the mailing lists? Regardless, it would be nice to get at least +-0 from @mdickinson@rhettinger@tim-one. I'm +1 on this. |
rob-smallshire commented Mar 26, 2019
@skrah Yes. Guido gave a pronouncement on python-dev. |
mdickinson commented Mar 26, 2019
+1 in principle. I haven't reviewed the code changes, and am unlikely to have the bandwidth to do so in the near future. |
rob-smallshire commented Apr 7, 2019
@skrah Is there anything I can do to help move this along? |
skrah commented Apr 7, 2019
@rob-smallshire This is basically just waiting for review now that @mdickinson is also in favor. I probably have time to review this before the beta-1 release, which is 2019-05-27. |
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Mostly LGTM; a few comments and suggestions.
We'll need a "whatsnew" entry, and we're missing some ".. versionchanged: " notes in the documentation updates.
Objects/longobject.c Outdated
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Could we convert this to Argument Clinic? It seems somewhat trivial, but one advantage is having the docstring close to the definition. Another is having docstring consistency between int.is_integer and float.is_integer.
Lib/_pydecimal.py Outdated
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I suggest following the usual convention for optional arguments and passing the rounding mode by name (rounding=ROUND_FLOOR).
Lib/numbers.py Outdated
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Please can we replace this with something that isn't a question? Something like the other docstrings ("Return True if the operand is integral; otherwise return False.") would be fine. (Also applies to Rational.is_integer below.)
Lib/test/test_decimal.py Outdated
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Would it be worth adding a couple of tests for cases where the exponent isn't 0, e.g. Decimal("1e2") and Decimal("100e-2")? We should also test the behaviour for signalling NaNs
Ideally, we'd also test that no Decimal floating-point flags are ever raised. An easy way to do this would be to add some testcases to Lib/test/decimaltestdata/extra.decTest, which will check that exactly the flags mentioned are raised for each given testcase.
Doc/library/decimal.rst Outdated
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Please add a .. versionadded:: 3.10 note here and in the other relevant bits of documentation.
EDIT: edited the comment to update the version; the original suggestion of 3.8 is obviously out of date
bedevere-bot commented May 12, 2019
A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated. Once you have made the requested changes, please leave a comment on this pull request containing the phrase |
rob-smallshire commented Aug 22, 2019
I haven't had capacity to do the requisite changes for 3.8. I propose going for 3.9. |
csabella commented May 22, 2020
@rob-smallshire, please address @mdickinson's review comments. Once everything looks good, it will make it into whichever release is master at the time, which right now would be 3.10. Thanks! |
@csabella Will do. I've scheduled some time to dedicate to this in early June. |
eric-wieser commented Aug 20, 2020
@rob-smallshire, any plans to return? |
rob-smallshire commented Aug 20, 2020
@eric-wieser Yes, absolutely. I've been looking at the required changes. I'll be pushing updates soon. |
rob-smallshireforce-pushed the is_integer branch from e745028 to e6a66a7Comparerob-smallshire commented Sep 17, 2020
Status update: rebased to resume work on the outstanding issues. |
rob-smallshireforce-pushed the is_integer branch from e6a66a7 to 1cacea7Comparemdickinson commented Sep 18, 2020
Thanks! Please ping me when you're done with updates and ready for re-review. |
…loat.is_integer(). The int.is_integer() method always returns True.
…integer() are always True.
rob-smallshireforce-pushed the is_integer branch from 1cacea7 to 138f704Compare
Lib/numbers.py Outdated
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Must denominator and numerator always be fully reduced?
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If not,
| returnself.denominator==1 | |
| returnself.numerator%self.denominator==0 |
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Yes, self.numerator and self.denominator will always be relatively prime in normal use (and denominator will always be positive). Other parts of the fractions module assume this, so it's safe to just check self.denominator == 1 here.
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This isn't about Fraction and its implementation of the Rational API though - this is about whether the API mandates the implementation behaves this way.
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Ah. I see the doc is """.numerator and .denominator should be in lowest terms.""" - so perhaps worth clarifying that denominator should always be positive too.
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Yes, that docstring could definitely be improved. Apart from that clarification, we could do with a line or two describing what the Rational class is actually for, rather than launching straight into a detail. But that's a job for a separate PR.
rob-smallshireforce-pushed the is_integer branch from 138f704 to a6a5490Compare… conversion to int. This default implementation is intended to reduce the workload for subclass implementers. It is not robust in the presence of infinities or NaNs and may have suboptimal performance for other types.
…ator is one. This implementation assumes the Rational is represented in it's lowest form, as required by the class docstring.
rob-smallshireforce-pushed the is_integer branch from 1ded358 to 821aad6Compare…t and float. The call x.is_integer() is now listed in the table of operations which apply to all numeric types except complex, with a reference to the full documentation for Real.is_integer(). Mention of is_integer() has been removed from the section 'Additional Methods on Float'. The documentation for Real.is_integer() describes its purpose, and mentions that it should be overridden for performance reasons, or to handle special values like NaN.
rob-smallshireforce-pushed the is_integer branch from 821aad6 to fba90b3CompareThe C implementation of Decimal already implements and uses mpd_isinteger internally, we just expose the existing function to Python. The Python implementation uses internal conversion to integer using to_integral_value(). In both cases, the corresponding context methods are also implemented. Tests and documentation are included.
rob-smallshireforce-pushed the is_integer branch from fba90b3 to 11db7f8Comparerob-smallshire commented Sep 18, 2020
@mdickinson I believe I now have made all the changes you requested, and all checks are passing. |
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LGTM. All my comments are addressed.
| .. method:: is_integer(x) | ||
| Returns ``True`` if *x* is finite and integral; otherwise |
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One day it would be nice to fix all these docstrings for consistency (both with one another and with PEP 257). But not today.
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Indeed, when you hop around the code you notice how different they all are. I tried to go for local consistency rather than global consistency.
mdickinson commented Sep 19, 2020
I'll leave this open for a couple of days in case @rhettinger or @skrah has further comments. |
rob-smallshire commented Oct 1, 2020
Anything I can do to help get this merged @mdickinson ? |
mdickinson commented Oct 1, 2020
Apart from pinging me in case I've forgotten? Nothing else I can think of ... Merging shortly. Thank you! |
bedevere-bot commented Oct 1, 2020
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mdickinson commented Oct 1, 2020
It seems rather unlikely that that buildbot failure is related (test_asyncio changed the environment). But it's odd that I don't see the same buildbot failure on other recent PRs. |
rhettinger commented Oct 4, 2020
Why was this merged? Guido was clear, "It should not go on the numeric tower." |
* origin/master: (147 commits) Fix the attribute names in the docstring of GenericAlias (pythonGH-22594) bpo-39337: Add a test case for normalizing of codec names (pythonGH-19069) bpo-41557: Update Windows installer to use SQLite 3.33.0 (pythonGH-21960) bpo-41976: Fix the fallback to gcc of ctypes.util.find_library when using gcc>9 (pythonGH-22598) bpo-41306: Allow scale value to not be rounded (pythonGH-21715) bpo-41970: Avoid test failure in test_lib2to3 if the module is already imported (pythonGH-22595) bpo-41376: Fix the documentation of `site.getusersitepackages()` (pythonGH-21602) Revert "bpo-26680: Incorporate is_integer in all built-in and standard library numeric types (pythonGH-6121)" (pythonGH-22584) bpo-41923: PEP 613: Add TypeAlias to typing module (python#22532) Fix comment about PyObject_IsTrue. (pythonGH-22343) bpo-38605: Make 'from __future__ import annotations' the default (pythonGH-20434) bpo-41905: Add abc.update_abstractmethods() (pythonGH-22485) bpo-41944: No longer call eval() on content received via HTTP in the UnicodeNames tests (pythonGH-22575) bpo-41944: No longer call eval() on content received via HTTP in the CJK codec tests (pythonGH-22566) Post 3.10.0a1 Python 3.10.0a1 bpo-41584: clarify when the reflected method of a binary arithemtic operator is called (python#22505) bpo-41939: Fix test_site.test_license_exists_at_url() (python#22559) bpo-41774: Tweak new programming FAQ entry (pythonGH-22562) bpo-41936. Remove macros Py_ALLOW_RECURSION/Py_END_ALLOW_RECURSION (pythonGH-22552) ...
…y numeric types (pythonGH-6121) * bpo-26680: Adds support for int.is_integer() for compatibility with float.is_integer(). The int.is_integer() method always returns True. * bpo-26680: Adds a test to ensure that False.is_integer() and True.is_integer() are always True. * bpo-26680: Adds Real.is_integer() with a trivial implementation using conversion to int. This default implementation is intended to reduce the workload for subclass implementers. It is not robust in the presence of infinities or NaNs and may have suboptimal performance for other types. * bpo-26680: Adds Rational.is_integer which returns True if the denominator is one. This implementation assumes the Rational is represented in it's lowest form, as required by the class docstring. * bpo-26680: Adds Integral.is_integer which always returns True. * bpo-26680: Adds tests for Fraction.is_integer called as an instance method. The tests for the Rational abstract base class use an unbound method to sidestep the inability to directly instantiate Rational. These tests check that everything works correct as an instance method. * bpo-26680: Updates documentation for Real.is_integer and built-ins int and float. The call x.is_integer() is now listed in the table of operations which apply to all numeric types except complex, with a reference to the full documentation for Real.is_integer(). Mention of is_integer() has been removed from the section 'Additional Methods on Float'. The documentation for Real.is_integer() describes its purpose, and mentions that it should be overridden for performance reasons, or to handle special values like NaN. * bpo-26680: Adds Decimal.is_integer to the Python and C implementations. The C implementation of Decimal already implements and uses mpd_isinteger internally, we just expose the existing function to Python. The Python implementation uses internal conversion to integer using to_integral_value(). In both cases, the corresponding context methods are also implemented. Tests and documentation are included. * bpo-26680: Updates the ACKS file. * bpo-26680: NEWS entries for int, the numeric ABCs and Decimal. Co-authored-by: Robert Smallshire <rob@sixty-north.com>
…d library numeric types (pythonGH-6121)" (pythonGH-22584) This reverts commit 58a7da9.
Match `int.is_integer`, which was added in python/cpython#6121
Match `int.is_integer`, which was added in python/cpython#6121
8 participants
This change implements support for the
x.is_integer()predicate across all built-in and standard library concrete numeric types:int,bool,FractionandDecimal; previously it was supported only onfloat. It also incorporatesis_integer()into the abstract typesReal,RationalandIntegral, with appropriate default implementations at each level.Updates to the relevant documentation and test suites are included.
https://bugs.python.org/issue26680