From 30d94b7aea69440605cc7d65e06ac374c25c74c1 Mon Sep 17 00:00:00 2001 From: Nadeem Vawda Date: Sat, 11 Feb 2012 23:45:10 +0200 Subject: [PATCH] Issue #13989: Document that GzipFile does not support text mode. Also, give a more helpful error message when opened with an invalid mode string. --- Doc/library/gzip.rst | 8 +++++--- Lib/gzip.py | 11 +++++++---- Misc/NEWS | 3 +++ 3 files changed, 15 insertions(+), 7 deletions(-) diff --git a/Doc/library/gzip.rst b/Doc/library/gzip.rst index 8aca2dd9564..9422ea9943a 100644 --- a/Doc/library/gzip.rst +++ b/Doc/library/gzip.rst @@ -44,9 +44,11 @@ The module defines the following items: The *mode* argument can be any of ``'r'``, ``'rb'``, ``'a'``, ``'ab'``, ``'w'``, or ``'wb'``, depending on whether the file will be read or written. The default - is the mode of *fileobj* if discernible; otherwise, the default is ``'rb'``. If - not given, the 'b' flag will be added to the mode to ensure the file is opened - in binary mode for cross-platform portability. + is the mode of *fileobj* if discernible; otherwise, the default is ``'rb'``. + + Note that the file is always opened in binary mode; text mode is not + supported. If you need to read a compressed file in text mode, wrap your + :class:`GzipFile` with an :class:`io.TextIOWrapper`. The *compresslevel* argument is an integer from ``1`` to ``9`` controlling the level of compression; ``1`` is fastest and produces the least compression, and diff --git a/Lib/gzip.py b/Lib/gzip.py index 4462187116d..1de23b6972f 100644 --- a/Lib/gzip.py +++ b/Lib/gzip.py @@ -105,6 +105,9 @@ class GzipFile(io.BufferedIOBase): """The GzipFile class simulates most of the methods of a file object with the exception of the readinto() and truncate() methods. + This class only supports opening files in binary mode. If you need to open a + compressed file in text mode, wrap your GzipFile with an io.TextIOWrapper. + """ myfileobj = None @@ -131,8 +134,8 @@ class GzipFile(io.BufferedIOBase): The mode argument can be any of 'r', 'rb', 'a', 'ab', 'w', or 'wb', depending on whether the file will be read or written. The default is the mode of fileobj if discernible; otherwise, the default is 'rb'. - Be aware that only the 'rb', 'ab', and 'wb' values should be used - for cross-platform portability. + A mode of 'r' is equivalent to one of 'rb', and similarly for 'w' and + 'wb', and 'a' and 'ab'. The compresslevel argument is an integer from 1 to 9 controlling the level of compression; 1 is fastest and produces the least compression, @@ -149,8 +152,8 @@ class GzipFile(io.BufferedIOBase): """ - # guarantee the file is opened in binary mode on platforms - # that care about that sort of thing + if mode and ('t' in mode or 'U' in mode): + raise IOError("Mode " + mode + " not supported") if mode and 'b' not in mode: mode += 'b' if fileobj is None: diff --git a/Misc/NEWS b/Misc/NEWS index da90e9e16bb..f45da7596eb 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -113,6 +113,9 @@ Core and Builtins Library ------- +- Issue #13989: Document that GzipFile does not support text mode, and give a + more helpful error message when opened with an invalid mode string. + - Issue #13590: On OS X 10.7 and 10.6 with Xcode 4.2, building Distutils-based packages with C extension modules may fail because Apple has removed gcc-4.2, the version used to build python.org