Merged revisions 76896,76898 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
........
r76896 | antoine.pitrou | 2009-12-19 22:01:10 +0100 (sam., 19 déc. 2009) | 3 lines
Issue #7545: improve documentation of the `buffering` argument in io.open().
........
r76898 | antoine.pitrou | 2009-12-19 22:06:36 +0100 (sam., 19 déc. 2009) | 3 lines
Remove superfetatory paragraph (left there by mistake).
........
diff --git a/Doc/library/io.rst b/Doc/library/io.rst
index 8fb984e..90573bd 100644
--- a/Doc/library/io.rst
+++ b/Doc/library/io.rst
@@ -96,10 +96,20 @@
strings, the bytes having been first decoded using a platform-dependent
encoding or using the specified *encoding* if given.
- *buffering* is an optional integer used to set the buffering policy. By
- default full buffering is on. Pass 0 to switch buffering off (only allowed
- in binary mode), 1 to set line buffering, and an integer > 1 to indicate the
- size of the buffer.
+ *buffering* is an optional integer used to set the buffering policy.
+ Pass 0 to switch buffering off (only allowed in binary mode), 1 to select
+ line buffering (only usable in text mode), and an integer > 1 to indicate
+ the size of a fixed-size chunk buffer. When no *buffering* argument is
+ given, the default buffering policy works as follows:
+
+ * Binary files are buffered in fixed-size chunks; the size of the buffer
+ is chosen using a heuristic trying to determine the underlying device's
+ "block size" and falling back on :attr:`DEFAULT_BUFFER_SIZE`.
+ On many systems, the buffer will typically be 4096 or 8192 bytes long.
+
+ * "Interactive" text files (files for which :meth:`isatty` returns True)
+ use line buffering. Other text files use the policy described above
+ for binary files.
*encoding* is the name of the encoding used to decode or encode the file.
This should only be used in text mode. The default encoding is platform
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index 04aed8d..a4beb2b 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -82,10 +82,20 @@
returned as strings, the bytes having been first decoded using a
platform-dependent encoding or using the specified encoding if given.
- buffering is an optional integer used to set the buffering policy. By
- default full buffering is on. Pass 0 to switch buffering off (only
- allowed in binary mode), 1 to set line buffering, and an integer > 1
- for full buffering.
+ buffering is an optional integer used to set the buffering policy.
+ Pass 0 to switch buffering off (only allowed in binary mode), 1 to select
+ line buffering (only usable in text mode), and an integer > 1 to indicate
+ the size of a fixed-size chunk buffer. When no buffering argument is
+ given, the default buffering policy works as follows:
+
+ * Binary files are buffered in fixed-size chunks; the size of the buffer
+ is chosen using a heuristic trying to determine the underlying device's
+ "block size" and falling back on `io.DEFAULT_BUFFER_SIZE`.
+ On many systems, the buffer will typically be 4096 or 8192 bytes long.
+
+ * "Interactive" text files (files for which isatty() returns True)
+ use line buffering. Other text files use the policy described above
+ for binary files.
encoding is the name of the encoding used to decode or encode the
file. This should only be used in text mode. The default encoding is
diff --git a/Modules/_io/_iomodule.c b/Modules/_io/_iomodule.c
index dfd66aa..14a4356 100644
--- a/Modules/_io/_iomodule.c
+++ b/Modules/_io/_iomodule.c
@@ -219,10 +219,20 @@
"returned as strings, the bytes having been first decoded using a\n"
"platform-dependent encoding or using the specified encoding if given.\n"
"\n"
-"buffering is an optional integer used to set the buffering policy. By\n"
-"default full buffering is on. Pass 0 to switch buffering off (only\n"
-"allowed in binary mode), 1 to set line buffering, and an integer > 1\n"
-"for full buffering.\n"
+"buffering is an optional integer used to set the buffering policy.\n"
+"Pass 0 to switch buffering off (only allowed in binary mode), 1 to select\n"
+"line buffering (only usable in text mode), and an integer > 1 to indicate\n"
+"the size of a fixed-size chunk buffer. When no buffering argument is\n"
+"given, the default buffering policy works as follows:\n"
+"\n"
+"* Binary files are buffered in fixed-size chunks; the size of the buffer\n"
+" is chosen using a heuristic trying to determine the underlying device's\n"
+" \"block size\" and falling back on `io.DEFAULT_BUFFER_SIZE`.\n"
+" On many systems, the buffer will typically be 4096 or 8192 bytes long.\n"
+"\n"
+"* \"Interactive\" text files (files for which isatty() returns True)\n"
+" use line buffering. Other text files use the policy described above\n"
+" for binary files.\n"
"\n"
"encoding is the name of the encoding used to decode or encode the\n"
"file. This should only be used in text mode. The default encoding is\n"