New submission from Serhiy Storchaka: Proposed patch replaces calls of public function PyUnicode_CompareWithASCIIString() with new private function _PyUnicode_EqualToASCIIString(). The problem with PyUnicode_CompareWithASCIIString() is that it returns -1 for the result "less than" and error, but the error case is never checked. The patch is purposed for following purposes:
1. Readability. ``_PyUnicode_EqualToASCIIString(...)`` looks more readable than ``PyUnicode_CompareWithASCIIString(...) == 0`` or ``!PyUnicode_CompareWithASCIIString(...)``, especially in large expression. I always have to make an effort to understand correctly the meaning of the latter expression. 2. Efficiency. If the strings are not equal, _PyUnicode_EqualToASCIIString() can quickly return false, but PyUnicode_CompareWithASCIIString() needs to check whether what string is larger. 3. Correctness. Since no caller checks the error of PyUnicode_CompareWithASCIIString(), it is incorrectly interpreted as "less then". Exception set by PyUnicode_CompareWithASCIIString() can be leaked in following code causing mystical error or crash in debug build. There are too many callers to add error checking for them all. These would be non-trivial error-prone changes that add new lines of the code, new variables and new returns or gotos. On other hand replacing PyUnicode_CompareWithASCIIString() with _PyUnicode_EqualToASCIIString() is done by simple script. _PyUnicode_EqualToASCIIString() returns true value (1) if strings are equal, false value (0) if they are different, and doesn't raise exceptions. Unlike to PyUnicode_CompareWithASCIIString() it works only with ASCII characters and returns false if any string contains non-ASCII characters. The patch also documents the return value of PyUnicode_CompareWithASCIIString() in case of error. See issue21449 for similar issue with _PyUnicode_CompareWithId(). ---------- components: Interpreter Core, Unicode files: _PyUnicode_EqualToASCIIString.patch keywords: patch messages: 280882 nosy: ezio.melotti, haypo, josh.r, serhiy.storchaka, xiang.zhang priority: normal severity: normal stage: patch review status: open title: Replace PyUnicode_CompareWithASCIIString with _PyUnicode_EqualToASCIIString type: behavior versions: Python 2.7, Python 3.5, Python 3.6, Python 3.7 Added file: http://bugs.python.org/file45490/_PyUnicode_EqualToASCIIString.patch _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue28701> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
