[Python-checkins] bpo-28286: Deprecate opening GzipFile for writing implicitly. (GH-16417)
Serhiy Storchaka
webhook-mailer at python.org
Sat Nov 16 11:57:01 EST 2019
https://github.com/python/cpython/commit/a0652328a26757a90d63697b5c01f5427b1132b5
commit: a0652328a26757a90d63697b5c01f5427b1132b5
branch: master
author: Serhiy Storchaka <storchaka at gmail.com>
committer: GitHub <noreply at github.com>
date: 2019-11-16T18:56:57+02:00
summary:
bpo-28286: Deprecate opening GzipFile for writing implicitly. (GH-16417)
Always specify the mode argument for writing.
files:
A Misc/NEWS.d/next/Library/2019-09-26-12-16-30.bpo-28286.LdSsrN.rst
M Doc/library/gzip.rst
M Doc/whatsnew/3.9.rst
M Lib/gzip.py
M Lib/test/test_gzip.py
diff --git a/Doc/library/gzip.rst b/Doc/library/gzip.rst
index 3349a94446d0c..33c40676f747c 100644
--- a/Doc/library/gzip.rst
+++ b/Doc/library/gzip.rst
@@ -88,7 +88,8 @@ The module defines the following items:
The *mode* argument can be any of ``'r'``, ``'rb'``, ``'a'``, ``'ab'``, ``'w'``,
``'wb'``, ``'x'``, or ``'xb'``, depending on whether the file will be read or
written. The default is the mode of *fileobj* if discernible; otherwise, the
- default is ``'rb'``.
+ default is ``'rb'``. In future Python releases the mode of *fileobj* will
+ not be used. It is better to always specify *mode* for writing.
Note that the file is always opened in binary mode. To open a compressed file
in text mode, use :func:`.open` (or wrap your :class:`GzipFile` with an
@@ -164,6 +165,10 @@ The module defines the following items:
.. versionchanged:: 3.6
Accepts a :term:`path-like object`.
+ .. deprecated:: 3.9
+ Opening :class:`GzipFile` for writing without specifying the *mode*
+ argument is deprecated.
+
.. function:: compress(data, compresslevel=9, *, mtime=None)
diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst
index 6e9ddc5684045..ddb295f845c75 100644
--- a/Doc/whatsnew/3.9.rst
+++ b/Doc/whatsnew/3.9.rst
@@ -239,6 +239,12 @@ Deprecated
the module will restrict its seeds to :const:`None`, :class:`int`,
:class:`float`, :class:`str`, :class:`bytes`, and :class:`bytearray`.
+* Opening the :class:`~gzip.GzipFile` file for writing without specifying
+ the *mode* argument is deprecated. In future Python versions it will always
+ be opened for reading by default. Specify the *mode* argument for opening
+ it for writing and silencing a warning.
+ (Contributed by Serhiy Storchaka in :issue:`28286`.)
+
* Deprecated the ``split()`` method of :class:`_tkinter.TkappType` in
favour of the ``splitlist()`` method which has more consistent and
predicable behavior.
diff --git a/Lib/gzip.py b/Lib/gzip.py
index 2968f475efad3..e60d8ad5995b3 100644
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -177,6 +177,7 @@ def __init__(self, filename=None, mode=None,
filename = ''
else:
filename = os.fspath(filename)
+ origmode = mode
if mode is None:
mode = getattr(fileobj, 'mode', 'rb')
@@ -187,6 +188,13 @@ def __init__(self, filename=None, mode=None,
self.name = filename
elif mode.startswith(('w', 'a', 'x')):
+ if origmode is None:
+ import warnings
+ warnings.warn(
+ "GzipFile was opened for writing, but this will "
+ "change in future Python releases. "
+ "Specify the mode argument for opening it for writing.",
+ FutureWarning, 2)
self.mode = WRITE
self._init_write(filename)
self.compress = zlib.compressobj(compresslevel,
diff --git a/Lib/test/test_gzip.py b/Lib/test/test_gzip.py
index 48a36a30913f6..57d851cf9cf15 100644
--- a/Lib/test/test_gzip.py
+++ b/Lib/test/test_gzip.py
@@ -469,7 +469,9 @@ def test_fileobj_mode(self):
if "x" in mode:
support.unlink(self.filename)
with open(self.filename, mode) as f:
- with gzip.GzipFile(fileobj=f) as g:
+ with self.assertWarns(FutureWarning):
+ g = gzip.GzipFile(fileobj=f)
+ with g:
self.assertEqual(g.mode, gzip.WRITE)
def test_bytes_filename(self):
diff --git a/Misc/NEWS.d/next/Library/2019-09-26-12-16-30.bpo-28286.LdSsrN.rst b/Misc/NEWS.d/next/Library/2019-09-26-12-16-30.bpo-28286.LdSsrN.rst
new file mode 100644
index 0000000000000..ee9721587eeb9
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-09-26-12-16-30.bpo-28286.LdSsrN.rst
@@ -0,0 +1,2 @@
+Deprecate opening :class:`~gzip.GzipFile` for writing implicitly. Always
+specify the *mode* argument for writing.
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