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PEP 682: small additions (#2322) 

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
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John Belmonte 2022-02-14 22:42:32 +09:00 committed by GitHub
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@ -111,8 +111,13 @@ std::format()`_. While the proposal was withdrawn for C++20, a consensus
proposal is promised for C++23. (The original `feature request`_ prompting
this PEP was argued without knowledge of the C++ proposal.)
When Rust developers debated whether to suppress negative zero in ``print``
output, they took a small `survey of other languages`_. Notably, it didn't
mention any language providing an option for negative zero handling.
.. _`proposed for C++ std::format()`: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p1496r2.pdf
.. _`feature request`: https://bugs.python.org/issue45995
.. _`survey of other languages`: https://github.com/rust-lang/rfcs/issues/1074#issuecomment-718243936
Specification
@ -125,7 +130,8 @@ An optional, literal ``z`` is added to the
[[fill]align][sign][z][#][0][width][grouping_option][.precision][type]
where ``z`` is allowed for numerical types other than integer. Support for
where ``z`` is allowed for floating-point presentation types (``f``, ``g``,
etc., as defined by the format specification documentation). Support for
``z`` is provided by the ``.__format__()`` method of each numeric type,
allowing the specifier to be used in f-strings, built-in ``format()``, and
``str.format()``. The %-formatting style will not support the new option.
@ -159,6 +165,12 @@ the new option, %-formatting cannot. There is already precedent for not
extending %-formatting with new options, as was the case for the
``,`` option (:pep:`378`).
C99 ``printf`` already uses the ``z`` option character for another
purpose: qualifying the unsigned type (``u``) to match the length of
``size_t``. However, since the signed zero option specifically disallows
``z`` for integer presentation types, it's possible to disambiguate the two
uses, should C want to adopt this new option.
Backwards Compatibility
=======================