Mailman 3 February 2020 - Python-checkins

bpo-39576: docs: set context for decimal arbitrary precision arithmetic (GH-18594) (#18596)
by Miss Islington (bot) 21 Feb '20

21 Feb '20

https://github.com/python/cpython/commit/00e45877e33d32bb61aa13a2033e3bba37… commit: 00e45877e33d32bb61aa13a2033e3bba370bda4d branch: 3.7 author: Miss Islington (bot) <31488909+miss-islington(a)users.noreply.github.com> committer: GitHub <noreply(a)github.com> date: 2020-02-21T21:36:02+01:00 summary: bpo-39576: docs: set context for decimal arbitrary precision arithmetic (GH-18594) (#18596) (cherry picked from commit a025d4ca99fb4c652465368e0b4eb03cf4b316b9) Authored-by: Stefan Krah <skrah(a)bytereef.org> files: M Doc/library/decimal.rst diff --git a/Doc/library/decimal.rst b/Doc/library/decimal.rst index bcae55eb82178..2a51429bdff5c 100644 --- a/Doc/library/decimal.rst +++ b/Doc/library/decimal.rst @@ -2121,17 +2121,67 @@ Q. Is the CPython implementation fast for large numbers? A. Yes. In the CPython and PyPy3 implementations, the C/CFFI versions of the decimal module integrate the high speed `libmpdec <https://www.bytereef.org/mpdecimal/doc/libmpdec/index.html>`_ library for -arbitrary precision correctly-rounded decimal floating point arithmetic. +arbitrary precision correctly-rounded decimal floating point arithmetic [#]_. ``libmpdec`` uses `Karatsuba multiplication <https://en.wikipedia.org/wiki/Karatsuba_algorithm>`_ for medium-sized numbers and the `Number Theoretic Transform <https://en.wikipedia.org/wiki/Discrete_Fourier_transform_(general)#Number-t…>`_ -for very large numbers. However, to realize this performance gain, the -context needs to be set for unrounded calculations. +for very large numbers. - >>> c = getcontext() - >>> c.prec = MAX_PREC - >>> c.Emax = MAX_EMAX - >>> c.Emin = MIN_EMIN +The context must be adapted for exact arbitrary precision arithmetic. :attr:`Emin` +and :attr:`Emax` should always be set to the maximum values, :attr:`clamp` +should always be 0 (the default). Setting :attr:`prec` requires some care. -.. versionadded:: 3.3 \ No newline at end of file +The easiest approach for trying out bignum arithmetic is to use the maximum +value for :attr:`prec` as well [#]_:: + + >>> setcontext(Context(prec=MAX_PREC, Emax=MAX_EMAX, Emin=MIN_EMIN)) + >>> x = Decimal(2) ** 256 + >>> x / 128 + Decimal('904625697166532776746648320380374280103671755200316906558262375061821325312') + + +For inexact results, :attr:`MAX_PREC` is far too large on 64-bit platforms and +the available memory will be insufficient:: + + >>> Decimal(1) / 3 + Traceback (most recent call last): + File "<stdin>", line 1, in <module> + MemoryError + +On systems with overallocation (e.g. Linux), a more sophisticated approach is to +adjust :attr:`prec` to the amount of available RAM. Suppose that you have 8GB of +RAM and expect 10 simultaneous operands using a maximum of 500MB each:: + + >>> import sys + >>> + >>> # Maximum number of digits for a single operand using 500MB in 8 byte words + >>> # with 19 (9 for the 32-bit version) digits per word: + >>> maxdigits = 19 * ((500 * 1024**2) // 8) + >>> + >>> # Check that this works: + >>> c = Context(prec=maxdigits, Emax=MAX_EMAX, Emin=MIN_EMIN) + >>> c.traps[Inexact] = True + >>> setcontext(c) + >>> + >>> # Fill the available precision with nines: + >>> x = Decimal(0).logical_invert() * 9 + >>> sys.getsizeof(x) + 524288112 + >>> x + 2 + Traceback (most recent call last): + File "<stdin>", line 1, in <module> + decimal.Inexact: [<class 'decimal.Inexact'>] + +In general (and especially on systems without overallocation), it is recommended +to estimate even tighter bounds and set the :attr:`Inexact` trap if all calculations +are expected to be exact. + + +.. [#] + .. versionadded:: 3.3 + +.. [#] + .. versionchanged:: 3.9 + This approach now works for all exact results except for non-integer powers. + Also backported to 3.7 and 3.8.

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bpo-39576: docs: set context for decimal arbitrary precision arithmetic (#18594)
by Stefan Krah 21 Feb '20

21 Feb '20

https://github.com/python/cpython/commit/a025d4ca99fb4c652465368e0b4eb03cf4… commit: a025d4ca99fb4c652465368e0b4eb03cf4b316b9 branch: master author: Stefan Krah <skrah(a)bytereef.org> committer: GitHub <noreply(a)github.com> date: 2020-02-21T21:27:37+01:00 summary: bpo-39576: docs: set context for decimal arbitrary precision arithmetic (#18594) files: M Doc/library/decimal.rst diff --git a/Doc/library/decimal.rst b/Doc/library/decimal.rst index bcae55eb82178..2a51429bdff5c 100644 --- a/Doc/library/decimal.rst +++ b/Doc/library/decimal.rst @@ -2121,17 +2121,67 @@ Q. Is the CPython implementation fast for large numbers? A. Yes. In the CPython and PyPy3 implementations, the C/CFFI versions of the decimal module integrate the high speed `libmpdec <https://www.bytereef.org/mpdecimal/doc/libmpdec/index.html>`_ library for -arbitrary precision correctly-rounded decimal floating point arithmetic. +arbitrary precision correctly-rounded decimal floating point arithmetic [#]_. ``libmpdec`` uses `Karatsuba multiplication <https://en.wikipedia.org/wiki/Karatsuba_algorithm>`_ for medium-sized numbers and the `Number Theoretic Transform <https://en.wikipedia.org/wiki/Discrete_Fourier_transform_(general)#Number-t…>`_ -for very large numbers. However, to realize this performance gain, the -context needs to be set for unrounded calculations. +for very large numbers. - >>> c = getcontext() - >>> c.prec = MAX_PREC - >>> c.Emax = MAX_EMAX - >>> c.Emin = MIN_EMIN +The context must be adapted for exact arbitrary precision arithmetic. :attr:`Emin` +and :attr:`Emax` should always be set to the maximum values, :attr:`clamp` +should always be 0 (the default). Setting :attr:`prec` requires some care. -.. versionadded:: 3.3 \ No newline at end of file +The easiest approach for trying out bignum arithmetic is to use the maximum +value for :attr:`prec` as well [#]_:: + + >>> setcontext(Context(prec=MAX_PREC, Emax=MAX_EMAX, Emin=MIN_EMIN)) + >>> x = Decimal(2) ** 256 + >>> x / 128 + Decimal('904625697166532776746648320380374280103671755200316906558262375061821325312') + + +For inexact results, :attr:`MAX_PREC` is far too large on 64-bit platforms and +the available memory will be insufficient:: + + >>> Decimal(1) / 3 + Traceback (most recent call last): + File "<stdin>", line 1, in <module> + MemoryError + +On systems with overallocation (e.g. Linux), a more sophisticated approach is to +adjust :attr:`prec` to the amount of available RAM. Suppose that you have 8GB of +RAM and expect 10 simultaneous operands using a maximum of 500MB each:: + + >>> import sys + >>> + >>> # Maximum number of digits for a single operand using 500MB in 8 byte words + >>> # with 19 (9 for the 32-bit version) digits per word: + >>> maxdigits = 19 * ((500 * 1024**2) // 8) + >>> + >>> # Check that this works: + >>> c = Context(prec=maxdigits, Emax=MAX_EMAX, Emin=MIN_EMIN) + >>> c.traps[Inexact] = True + >>> setcontext(c) + >>> + >>> # Fill the available precision with nines: + >>> x = Decimal(0).logical_invert() * 9 + >>> sys.getsizeof(x) + 524288112 + >>> x + 2 + Traceback (most recent call last): + File "<stdin>", line 1, in <module> + decimal.Inexact: [<class 'decimal.Inexact'>] + +In general (and especially on systems without overallocation), it is recommended +to estimate even tighter bounds and set the :attr:`Inexact` trap if all calculations +are expected to be exact. + + +.. [#] + .. versionadded:: 3.3 + +.. [#] + .. versionchanged:: 3.9 + This approach now works for all exact results except for non-integer powers. + Also backported to 3.7 and 3.8.

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bpo-35950: Raise UnsupportedOperation in BufferedReader.truncate() (GH-18586)
by Berker Peksag 21 Feb '20

21 Feb '20

https://github.com/python/cpython/commit/fd5116c0e77aec05f67fb24f10562ac920… commit: fd5116c0e77aec05f67fb24f10562ac920648035 branch: master author: Berker Peksag <berker.peksag(a)gmail.com> committer: GitHub <noreply(a)github.com> date: 2020-02-21T09:57:26-08:00 summary: bpo-35950: Raise UnsupportedOperation in BufferedReader.truncate() (GH-18586) The truncate() method of io.BufferedReader() should raise UnsupportedOperation when it is called on a read-only io.BufferedReader() instance. https://bugs.python.org/issue35950 Automerge-Triggered-By: @methane files: A Misc/NEWS.d/next/Library/2020-02-21-02-42-41.bpo-35950.9G3-wl.rst M Lib/_pyio.py M Lib/test/test_io.py M Modules/_io/bufferedio.c diff --git a/Lib/_pyio.py b/Lib/_pyio.py index 4c2414672ed56..8eaa114c07c91 100644 --- a/Lib/_pyio.py +++ b/Lib/_pyio.py @@ -792,6 +792,9 @@ def tell(self): return pos def truncate(self, pos=None): + self._checkClosed() + self._checkWritable() + # Flush the stream. We're mixing buffered I/O with lower-level I/O, # and a flush may be necessary to synch both views of the current # file state. diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py index 0bfa4d249e9a6..c27dfd96bc00d 100644 --- a/Lib/test/test_io.py +++ b/Lib/test/test_io.py @@ -1528,6 +1528,13 @@ def test_read_on_closed(self): self.assertRaises(ValueError, b.peek) self.assertRaises(ValueError, b.read1, 1) + def test_truncate_on_read_only(self): + rawio = self.MockFileIO(b"abc") + bufio = self.tp(rawio) + self.assertFalse(bufio.writable()) + self.assertRaises(self.UnsupportedOperation, bufio.truncate) + self.assertRaises(self.UnsupportedOperation, bufio.truncate, 0) + class CBufferedReaderTest(BufferedReaderTest, SizeofTest): tp = io.BufferedReader @@ -2372,6 +2379,10 @@ def test_interleaved_readline_write(self): # You can't construct a BufferedRandom over a non-seekable stream. test_unseekable = None + # writable() returns True, so there's no point to test it over + # a writable stream. + test_truncate_on_read_only = None + class CBufferedRandomTest(BufferedRandomTest, SizeofTest): tp = io.BufferedRandom diff --git a/Misc/NEWS.d/next/Library/2020-02-21-02-42-41.bpo-35950.9G3-wl.rst b/Misc/NEWS.d/next/Library/2020-02-21-02-42-41.bpo-35950.9G3-wl.rst new file mode 100644 index 0000000000000..92e3b2399238e --- /dev/null +++ b/Misc/NEWS.d/next/Library/2020-02-21-02-42-41.bpo-35950.9G3-wl.rst @@ -0,0 +1,2 @@ +Raise :exc:`io.UnsupportedOperation` in :meth:`io.BufferedReader.truncate` +when it is called on a read-only :class:`io.BufferedReader` instance. diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c index 6f55577813c9f..a09082c84f8a2 100644 --- a/Modules/_io/bufferedio.c +++ b/Modules/_io/bufferedio.c @@ -1315,15 +1315,19 @@ _io__Buffered_truncate_impl(buffered *self, PyObject *pos) PyObject *res = NULL; CHECK_INITIALIZED(self) + CHECK_CLOSED(self, "truncate of closed file") + if (!self->writable) { + return bufferediobase_unsupported("truncate"); + } if (!ENTER_BUFFERED(self)) return NULL; - if (self->writable) { - res = buffered_flush_and_rewind_unlocked(self); - if (res == NULL) - goto end; - Py_CLEAR(res); + res = buffered_flush_and_rewind_unlocked(self); + if (res == NULL) { + goto end; } + Py_CLEAR(res); + res = PyObject_CallMethodOneArg(self->raw, _PyIO_str_truncate, pos); if (res == NULL) goto end;

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fix(doc): set correct RST syntax for c:function (GH-18589)
by Miss Islington (bot) 21 Feb '20

21 Feb '20

https://github.com/python/cpython/commit/50ce89071d212e659818825522be48acda… commit: 50ce89071d212e659818825522be48acda4d2979 branch: 3.7 author: Miss Islington (bot) <31488909+miss-islington(a)users.noreply.github.com> committer: GitHub <noreply(a)github.com> date: 2020-02-21T06:09:24-08:00 summary: fix(doc): set correct RST syntax for c:function (GH-18589) The current content is not rendered since the syntax is not correct. (cherry picked from commit d4d17fd2cf69e7c8f4cd03fbf2d575370945b952) Co-authored-by: Julien Danjou <julien(a)danjou.info> files: M Doc/c-api/memory.rst diff --git a/Doc/c-api/memory.rst b/Doc/c-api/memory.rst index f14e1e123a0df..f4c94c4f3ce8d 100644 --- a/Doc/c-api/memory.rst +++ b/Doc/c-api/memory.rst @@ -533,7 +533,7 @@ tracemalloc C API .. versionadded:: 3.7 -.. c:function: int PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr, size_t size) +.. c:function:: int PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr, size_t size) Track an allocated memory block in the :mod:`tracemalloc` module. @@ -542,7 +542,7 @@ tracemalloc C API If memory block is already tracked, update the existing trace. -.. c:function: int PyTraceMalloc_Untrack(unsigned int domain, uintptr_t ptr) +.. c:function:: int PyTraceMalloc_Untrack(unsigned int domain, uintptr_t ptr) Untrack an allocated memory block in the :mod:`tracemalloc` module. Do nothing if the block was not tracked.

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fix(doc): set correct RST syntax for c:function (GH-18589)
by Miss Islington (bot) 21 Feb '20

21 Feb '20

https://github.com/python/cpython/commit/9ce361d3bb15cf49b82fa03e3e593d7cbd… commit: 9ce361d3bb15cf49b82fa03e3e593d7cbd8ee1ff branch: 3.8 author: Miss Islington (bot) <31488909+miss-islington(a)users.noreply.github.com> committer: GitHub <noreply(a)github.com> date: 2020-02-21T02:54:00-08:00 summary: fix(doc): set correct RST syntax for c:function (GH-18589) The current content is not rendered since the syntax is not correct. (cherry picked from commit d4d17fd2cf69e7c8f4cd03fbf2d575370945b952) Co-authored-by: Julien Danjou <julien(a)danjou.info> files: M Doc/c-api/memory.rst diff --git a/Doc/c-api/memory.rst b/Doc/c-api/memory.rst index ba7bd3b9a5387..8a8542f0479ec 100644 --- a/Doc/c-api/memory.rst +++ b/Doc/c-api/memory.rst @@ -533,7 +533,7 @@ tracemalloc C API .. versionadded:: 3.7 -.. c:function: int PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr, size_t size) +.. c:function:: int PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr, size_t size) Track an allocated memory block in the :mod:`tracemalloc` module. @@ -542,7 +542,7 @@ tracemalloc C API If memory block is already tracked, update the existing trace. -.. c:function: int PyTraceMalloc_Untrack(unsigned int domain, uintptr_t ptr) +.. c:function:: int PyTraceMalloc_Untrack(unsigned int domain, uintptr_t ptr) Untrack an allocated memory block in the :mod:`tracemalloc` module. Do nothing if the block was not tracked.

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fix(doc): set correct RST syntax for c:function (GH-18589)
by Julien Danjou 21 Feb '20

21 Feb '20

https://github.com/python/cpython/commit/d4d17fd2cf69e7c8f4cd03fbf2d5753709… commit: d4d17fd2cf69e7c8f4cd03fbf2d575370945b952 branch: master author: Julien Danjou <julien(a)danjou.info> committer: GitHub <noreply(a)github.com> date: 2020-02-21T11:47:41+01:00 summary: fix(doc): set correct RST syntax for c:function (GH-18589) The current content is not rendered since the syntax is not correct. files: M Doc/c-api/memory.rst diff --git a/Doc/c-api/memory.rst b/Doc/c-api/memory.rst index ba7bd3b9a5387..8a8542f0479ec 100644 --- a/Doc/c-api/memory.rst +++ b/Doc/c-api/memory.rst @@ -533,7 +533,7 @@ tracemalloc C API .. versionadded:: 3.7 -.. c:function: int PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr, size_t size) +.. c:function:: int PyTraceMalloc_Track(unsigned int domain, uintptr_t ptr, size_t size) Track an allocated memory block in the :mod:`tracemalloc` module. @@ -542,7 +542,7 @@ tracemalloc C API If memory block is already tracked, update the existing trace. -.. c:function: int PyTraceMalloc_Untrack(unsigned int domain, uintptr_t ptr) +.. c:function:: int PyTraceMalloc_Untrack(unsigned int domain, uintptr_t ptr) Untrack an allocated memory block in the :mod:`tracemalloc` module. Do nothing if the block was not tracked.

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bpo-35727: Use exit code 0 on sys.exit() in multiprocessing.Process. (GH-11538)
by Christopher Hunt 21 Feb '20

21 Feb '20

https://github.com/python/cpython/commit/c2ac4cf040ea950bf552d1e77bea613a1a… commit: c2ac4cf040ea950bf552d1e77bea613a1a5474fe branch: master author: Christopher Hunt <chrahunt(a)gmail.com> committer: GitHub <noreply(a)github.com> date: 2020-02-21T10:33:04+01:00 summary: bpo-35727: Use exit code 0 on sys.exit() in multiprocessing.Process. (GH-11538) files: A Misc/NEWS.d/next/Library/2019-01-12-20-39-34.bpo-35727.FWrbHn.rst M Lib/multiprocessing/process.py M Lib/test/_test_multiprocessing.py M Misc/ACKS diff --git a/Lib/multiprocessing/process.py b/Lib/multiprocessing/process.py index be13c079bb89b..0b2e0b45b2397 100644 --- a/Lib/multiprocessing/process.py +++ b/Lib/multiprocessing/process.py @@ -317,12 +317,12 @@ def _bootstrap(self, parent_sentinel=None): finally: util._exit_function() except SystemExit as e: - if not e.args: - exitcode = 1 - elif isinstance(e.args[0], int): - exitcode = e.args[0] + if e.code is None: + exitcode = 0 + elif isinstance(e.code, int): + exitcode = e.code else: - sys.stderr.write(str(e.args[0]) + '\n') + sys.stderr.write(str(e.code) + '\n') exitcode = 1 except: exitcode = 1 diff --git a/Lib/test/_test_multiprocessing.py b/Lib/test/_test_multiprocessing.py index 4e48cd45e14ca..73dc75d34a6f0 100644 --- a/Lib/test/_test_multiprocessing.py +++ b/Lib/test/_test_multiprocessing.py @@ -864,12 +864,21 @@ def test_sys_exit(self): os.unlink(testfn) - for reason in (True, False, 8): - p = self.Process(target=sys.exit, args=(reason,)) - p.daemon = True - p.start() - join_process(p) - self.assertEqual(p.exitcode, reason) + cases = [ + ((True,), 1), + ((False,), 0), + ((8,), 8), + ((None,), 0), + ((), 0), + ] + + for args, expected in cases: + with self.subTest(args=args): + p = self.Process(target=sys.exit, args=args) + p.daemon = True + p.start() + join_process(p) + self.assertEqual(p.exitcode, expected) # # diff --git a/Misc/ACKS b/Misc/ACKS index 976c26eb9117b..f329a2d4a7d33 100644 --- a/Misc/ACKS +++ b/Misc/ACKS @@ -746,6 +746,7 @@ Lawrence Hudson Michael Hudson Jim Hugunin Greg Humphreys +Chris Hunt Eric Huss Nehal Hussain Taihyun Hwang diff --git a/Misc/NEWS.d/next/Library/2019-01-12-20-39-34.bpo-35727.FWrbHn.rst b/Misc/NEWS.d/next/Library/2019-01-12-20-39-34.bpo-35727.FWrbHn.rst new file mode 100644 index 0000000000000..9f3fa40e51bf3 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2019-01-12-20-39-34.bpo-35727.FWrbHn.rst @@ -0,0 +1 @@ +Fix sys.exit() and sys.exit(None) exit code propagation when used in multiprocessing.Process. \ No newline at end of file

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Reuse identifier of PREDICT macros as PREDICT_ID (GH-17155)
by Denis Chernikov 21 Feb '20

21 Feb '20

https://github.com/python/cpython/commit/baf29b221682be0f4fde53a05ea3f57c3c… commit: baf29b221682be0f4fde53a05ea3f57c3c79f431 branch: master author: Denis Chernikov <tchernikoff.denis2013(a)yandex.ru> committer: GitHub <noreply(a)github.com> date: 2020-02-21T10:17:50+01:00 summary: Reuse identifier of PREDICT macros as PREDICT_ID (GH-17155) In function `_PyEval_EvalFrameDefault`, macros PREDICT and PREDICTED use the same identifier creation scheme, which may be shared between them, reducing code repetition, and do ensure that the same identifier is generated. files: M Python/ceval.c diff --git a/Python/ceval.c b/Python/ceval.c index 426d0bbee8901..3f65820c25da9 100644 --- a/Python/ceval.c +++ b/Python/ceval.c @@ -921,21 +921,23 @@ _PyEval_EvalFrameDefault(PyFrameObject *f, int throwflag) */ +#define PREDICT_ID(op) PRED_##op + #if defined(DYNAMIC_EXECUTION_PROFILE) || USE_COMPUTED_GOTOS -#define PREDICT(op) if (0) goto PRED_##op +#define PREDICT(op) if (0) goto PREDICT_ID(op) #else #define PREDICT(op) \ - do{ \ + do { \ _Py_CODEUNIT word = *next_instr; \ opcode = _Py_OPCODE(word); \ - if (opcode == op){ \ + if (opcode == op) { \ oparg = _Py_OPARG(word); \ next_instr++; \ - goto PRED_##op; \ + goto PREDICT_ID(op); \ } \ } while(0) #endif -#define PREDICTED(op) PRED_##op: +#define PREDICTED(op) PREDICT_ID(op): /* Stack manipulation macros */

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bpo-9495: avoid confusing chained exception in argparse test (GH-17120)
by alclarks 21 Feb '20

21 Feb '20

https://github.com/python/cpython/commit/d4331c56b4f6fe6f18caf19fc1ecf9fec1… commit: d4331c56b4f6fe6f18caf19fc1ecf9fec14f7066 branch: master author: alclarks <57201106+alclarks(a)users.noreply.github.com> committer: GitHub <noreply(a)github.com> date: 2020-02-21T10:48:36+02:00 summary: bpo-9495: avoid confusing chained exception in argparse test (GH-17120) files: M Lib/test/test_argparse.py M Misc/ACKS diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py index b095783a02e1e..9899a53d6d197 100644 --- a/Lib/test/test_argparse.py +++ b/Lib/test/test_argparse.py @@ -105,7 +105,8 @@ def stderr_to_parser_error(parse_args, *args, **kwargs): code = sys.exc_info()[1].code stdout = sys.stdout.getvalue() stderr = sys.stderr.getvalue() - raise ArgumentParserError("SystemExit", stdout, stderr, code) + raise ArgumentParserError( + "SystemExit", stdout, stderr, code) from None finally: sys.stdout = old_stdout sys.stderr = old_stderr diff --git a/Misc/ACKS b/Misc/ACKS index b11ee9cdea67d..976c26eb9117b 100644 --- a/Misc/ACKS +++ b/Misc/ACKS @@ -312,6 +312,7 @@ Gilles Civario Chris Clark Diana Clarke Laurie Clark-Michalek +Alexander Clarkson Mike Clarkson Andrew Clegg Brad Clements

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bpo-38657: Clarify numeric padding behaviour in string formatting (GH-17036)
by Miss Islington (bot) 21 Feb '20

21 Feb '20

https://github.com/python/cpython/commit/a2075121217e809c9a5511f6ca225c12f3… commit: a2075121217e809c9a5511f6ca225c12f340de0c branch: 3.8 author: Miss Islington (bot) <31488909+miss-islington(a)users.noreply.github.com> committer: GitHub <noreply(a)github.com> date: 2020-02-20T22:06:18-08:00 summary: bpo-38657: Clarify numeric padding behaviour in string formatting (GH-17036) Make the definition of the width more explicit that it includes any extra signs added by other options. https://bugs.python.org/issue38657 Automerge-Triggered-By: @Mariatta (cherry picked from commit 424e5686d82235e08f8108b8bbe034bc91421689) Co-authored-by: Pete Wicken <2273100+JamoBox(a)users.noreply.github.com> files: M Doc/library/string.rst diff --git a/Doc/library/string.rst b/Doc/library/string.rst index e2983db1ac832..89c169a512b52 100644 --- a/Doc/library/string.rst +++ b/Doc/library/string.rst @@ -415,8 +415,9 @@ error. .. versionchanged:: 3.6 Added the ``'_'`` option (see also :pep:`515`). -*width* is a decimal integer defining the minimum field width. If not -specified, then the field width will be determined by the content. +*width* is a decimal integer defining the minimum total field width, +including any prefixes, separators, and other formatting characters. +If not specified, then the field width will be determined by the content. When no explicit alignment is given, preceding the *width* field by a zero (``'0'``) character enables

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