mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-08-04 00:48:58 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 8

Issue #12760: Add a create mode to open(). Patch by David Townshend.

Browse source
This commit is contained in:
Charles-François Natali 2012-01-09 22:40:02 +01:00
parent 8a9b9c7d16
commit dc3044c704
9 changed files with 101 additions and 41 deletions
Download patch file Download diff file Expand all files Collapse all files

34
Lib/_pyio.py
View file

@ -38,21 +38,22 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
wrapped. (If a file descriptor is given, it is closed when the
returned I/O object is closed, unless closefd is set to False.)
mode is an optional string that specifies the mode in which the file
is opened. It defaults to 'r' which means open for reading in text
mode. Other common values are 'w' for writing (truncating the file if
it already exists), and 'a' for appending (which on some Unix systems,
means that all writes append to the end of the file regardless of the
current seek position). In text mode, if encoding is not specified the
encoding used is platform dependent. (For reading and writing raw
bytes use binary mode and leave encoding unspecified.) The available
modes are:
mode is an optional string that specifies the mode in which the file is
opened. It defaults to 'r' which means open for reading in text mode. Other
common values are 'w' for writing (truncating the file if it already
exists), 'x' for creating and writing to a new file, and 'a' for appending
(which on some Unix systems, means that all writes append to the end of the
file regardless of the current seek position). In text mode, if encoding is
not specified the encoding used is platform dependent. (For reading and
writing raw bytes use binary mode and leave encoding unspecified.) The
available modes are:
========= ===============================================================
Character Meaning
--------- ---------------------------------------------------------------
'r' open for reading (default)
'w' open for writing, truncating the file first
'x' create a new file and open it for writing
'a' open for writing, appending to the end of the file if it exists
'b' binary mode
't' text mode (default)
@ -63,7 +64,8 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
The default mode is 'rt' (open for reading text). For binary random
access, the mode 'w+b' opens and truncates the file to 0 bytes, while
'r+b' opens the file without truncation.
'r+b' opens the file without truncation. The 'x' mode implies 'w' and
raises an `FileExistsError` if the file already exists.
Python distinguishes between files opened in binary and text modes,
even when the underlying operating system doesn't. Files opened in
@ -154,8 +156,9 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
if errors is not None and not isinstance(errors, str):
raise TypeError("invalid errors: %r" % errors)
modes = set(mode)
if modes - set("arwb+tU") or len(mode) > len(modes):
if modes - set("axrwb+tU") or len(mode) > len(modes):
raise ValueError("invalid mode: %r" % mode)
creating = "x" in modes
reading = "r" in modes
writing = "w" in modes
appending = "a" in modes
@ -163,14 +166,14 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
text = "t" in modes
binary = "b" in modes
if "U" in modes:
if writing or appending:
if creating or writing or appending:
raise ValueError("can't use U and writing mode at once")
reading = True
if text and binary:
raise ValueError("can't have text and binary mode at once")
if reading + writing + appending > 1:
if creating + reading + writing + appending > 1:
raise ValueError("can't have read/write/append mode at once")
if not (reading or writing or appending):
if not (creating or reading or writing or appending):
raise ValueError("must have exactly one of read/write/append mode")
if binary and encoding is not None:
raise ValueError("binary mode doesn't take an encoding argument")
@ -179,6 +182,7 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
if binary and newline is not None:
raise ValueError("binary mode doesn't take a newline argument")
raw = FileIO(file,
(creating and "x" or "") +
(reading and "r" or "") +
(writing and "w" or "") +
(appending and "a" or "") +
@ -205,7 +209,7 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
raise ValueError("can't have unbuffered text I/O")
if updating:
buffer = BufferedRandom(raw, buffering)
elif writing or appending:
elif creating or writing or appending:
buffer = BufferedWriter(raw, buffering)
elif reading:
buffer = BufferedReader(raw, buffering)