[Python-checkins] cpython (merge 3.3 -> default): Issue #15677: Document that zlib and gzip accept a compression level of 0 to

Sun Nov 11 14:20:41 CET 2012

http://hg.python.org/cpython/rev/21335c9fcec0
changeset: 80388:21335c9fcec0
parent: 80381:d51df72dadb7
parent: 80387:0e48bf45313c
user: Nadeem Vawda <nadeem.vawda at gmail.com>
date: Sun Nov 11 14:20:09 2012 +0100
summary:
 Issue #15677: Document that zlib and gzip accept a compression level of 0 to mean 'no compression'.
Patch by Brian Brazil.
files:
 Doc/library/gzip.rst | 9 +++++----
 Doc/library/zlib.rst | 11 ++++++-----
 Lib/gzip.py | 7 ++++---
 Misc/NEWS | 3 +++
 Modules/zlibmodule.c | 4 ++--
 5 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/Doc/library/gzip.rst b/Doc/library/gzip.rst
--- a/Doc/library/gzip.rst
+++ b/Doc/library/gzip.rst
@@ -38,7 +38,7 @@
 ``'w'``, or ``'wb'`` for binary mode, or ``'rt'``, ``'at'``, or ``'wt'`` for
 text mode. The default is ``'rb'``.
 
- The *compresslevel* argument is an integer from 1 to 9, as for the
+ The *compresslevel* argument is an integer from 0 to 9, as for the
 :class:`GzipFile` constructor.
 
 For binary mode, this function is equivalent to the :class:`GzipFile`
@@ -80,9 +80,10 @@
 in text mode, use :func:`.open` (or 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
- ``9`` is slowest and produces the most compression. The default is ``9``.
+ The *compresslevel* argument is an integer from ``0`` to ``9`` controlling
+ the level of compression; ``1`` is fastest and produces the least
+ compression, and ``9`` is slowest and produces the most compression. ``0``
+ is no compression. The default is ``9``.
 
 The *mtime* argument is an optional numeric timestamp to be written to
 the stream when compressing. All :program:`gzip` compressed streams are
diff --git a/Doc/library/zlib.rst b/Doc/library/zlib.rst
--- a/Doc/library/zlib.rst
+++ b/Doc/library/zlib.rst
@@ -52,10 +52,10 @@
 .. function:: compress(data[, level])
 
 Compresses the bytes in *data*, returning a bytes object containing compressed data.
- *level* is an integer from ``1`` to ``9`` controlling the level of compression;
+ *level* is an integer from ``0`` to ``9`` controlling the level of compression;
 ``1`` is fastest and produces the least compression, ``9`` is slowest and
- produces the most. The default value is ``6``. Raises the :exc:`error`
- exception if any error occurs.
+ produces the most. ``0`` is no compression. The default value is ``6``.
+ Raises the :exc:`error` exception if any error occurs.
 
 
 .. function:: compressobj(level=-1, method=DEFLATED, wbits=15, memlevel=8, strategy=Z_DEFAULT_STRATEGY[, zdict])
@@ -63,9 +63,10 @@
 Returns a compression object, to be used for compressing data streams that won't
 fit into memory at once.
 
- *level* is the compression level -- an integer from ``1`` to ``9``. A value
+ *level* is the compression level -- an integer from ``0`` to ``9``. A value
 of ``1`` is fastest and produces the least compression, while a value of
- ``9`` is slowest and produces the most. The default value is ``6``.
+ ``9`` is slowest and produces the most. ``0`` is no compression. The default
+ value is ``6``.
 
 *method* is the compression algorithm. Currently, the only supported value is
 ``DEFLATED``.
diff --git a/Lib/gzip.py b/Lib/gzip.py
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -160,9 +160,10 @@
 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
+ The compresslevel argument is an integer from 0 to 9 controlling the
 level of compression; 1 is fastest and produces the least compression,
- and 9 is slowest and produces the most compression. The default is 9.
+ and 9 is slowest and produces the most compression. 0 is no compression
+ at all. The default is 9.
 
 The mtime argument is an optional numeric timestamp to be written
 to the stream when compressing. All gzip compressed streams
@@ -622,7 +623,7 @@
 
 def compress(data, compresslevel=9):
 """Compress data in one shot and return the compressed string.
- Optional argument is the compression level, in range of 1-9.
+ Optional argument is the compression level, in range of 0-9.
 """
 buf = io.BytesIO()
 with GzipFile(fileobj=buf, mode='wb', compresslevel=compresslevel) as f:
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -359,6 +359,9 @@
 Documentation
 -------------
 
+- Issue #15677: Document that zlib and gzip accept a compression level of 0 to
+ mean 'no compression'. Patch by Brian Brazil.
+
 - Issue #8040: added a version switcher to the documentation. Patch by
 Yury Selivanov.
 
diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -139,7 +139,7 @@
 PyDoc_STRVAR(compress__doc__,
 "compress(string[, level]) -- Returned compressed string.\n"
 "\n"
-"Optional arg level is the compression level, in 1-9.");
+"Optional arg level is the compression level, in 0-9.");
 
 static PyObject *
 PyZlib_compress(PyObject *self, PyObject *args)
@@ -1227,7 +1227,7 @@
 "zlib library, which is based on GNU zip.\n"
 "\n"
 "adler32(string[, start]) -- Compute an Adler-32 checksum.\n"
-"compress(string[, level]) -- Compress string, with compression level in 1-9.\n"
+"compress(string[, level]) -- Compress string, with compression level in 0-9.\n"
 "compressobj([level[, ...]]) -- Return a compressor object.\n"
 "crc32(string[, start]) -- Compute a CRC-32 checksum.\n"
 "decompress(string,[wbits],[bufsize]) -- Decompresses a compressed string.\n"
-- 
Repository URL: http://hg.python.org/cpython
