From bc144f0abff2b36595171377ee847c0266596ab2 Mon Sep 17 00:00:00 2001 From: Martijn Pieters Date: Mon, 27 Feb 2017 16:07:27 +0000 Subject: bpo-28598: Support __rmod__ for RHS subclasses of str in % string formatting operations (#94) --- Lib/test/test_unicode.py | 9 +++++++++ Misc/NEWS | 3 +++ Python/ceval.c | 12 +++++++++--- 3 files changed, 21 insertions(+), 3 deletions(-) diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py index 3136ea1..9dbded2 100644 --- a/Lib/test/test_unicode.py +++ b/Lib/test/test_unicode.py @@ -1424,6 +1424,15 @@ class UnicodeTest(string_tests.CommonTest, with self.assertRaises(ValueError): result = format_string % 2.34 + def test_issue28598_strsubclass_rhs(self): + # A subclass of str with an __rmod__ method should be able to hook + # into the % operator + class SubclassedStr(str): + def __rmod__(self, other): + return 'Success, self.__rmod__({!r}) was called'.format(other) + self.assertEqual('lhs %% %r' % SubclassedStr('rhs'), + "Success, self.__rmod__('lhs %% %r') was called") + @support.cpython_only def test_formatting_huge_precision_c_limits(self): from _testcapi import INT_MAX diff --git a/Misc/NEWS b/Misc/NEWS index 635f413..fd25a5f 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -10,6 +10,9 @@ Release date: XXXX-XX-XX Core and Builtins ----------------- +- Issue #28598: Support __rmod__ for subclasses of str being called before + str.__mod__. Patch by Martijn Pieters. + - bpo-29602: Fix incorrect handling of signed zeros in complex constructor for complex subclasses and for inputs having a __complex__ method. Patch by Serhiy Storchaka. diff --git a/Python/ceval.c b/Python/ceval.c index 7b40518..d323908 100644 --- a/Python/ceval.c +++ b/Python/ceval.c @@ -1545,9 +1545,15 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag) TARGET(BINARY_MODULO) { PyObject *divisor = POP(); PyObject *dividend = TOP(); - PyObject *res = PyUnicode_CheckExact(dividend) ? - PyUnicode_Format(dividend, divisor) : - PyNumber_Remainder(dividend, divisor); + PyObject *res; + if (PyUnicode_CheckExact(dividend) && ( + !PyUnicode_Check(divisor) || PyUnicode_CheckExact(divisor))) { + /* fast path; string formatting, but not if the RHS is a str subclass + (see issue28598) */ + res = PyUnicode_Format(dividend, divisor); + } else { + res = PyNumber_Remainder(dividend, divisor); + } Py_DECREF(divisor); Py_DECREF(dividend); SET_TOP(res); -- cgit v0.12