cpython-withatomic / Lib /

"""The io module provides the Python interfaces to stream handling. The
builtin open function is defined in this module.

At the top of the I/O hierarchy is the abstract base class IOBase. It
defines the basic interface to a stream. Note, however, that there is no
separation between reading and writing to streams; implementations are
allowed to throw an IOError if they do not support a given operation.

Extending IOBase is RawIOBase which deals simply with the reading and
writing of raw bytes to a stream. FileIO subclasses RawIOBase to provide
an interface to OS files.

BufferedIOBase deals with buffering on a raw byte stream (RawIOBase). Its
subclasses, BufferedWriter, BufferedReader, and BufferedRWPair buffer
streams that are readable, writable, and both respectively.
BufferedRandom provides a buffered interface to random access
streams. BytesIO is a simple stream of in-memory bytes.

Another IOBase subclass, TextIOBase, deals with the encoding and decoding
of streams into text. TextIOWrapper, which extends it, is a buffered text
interface to a buffered raw stream (`BufferedIOBase`). Finally, StringIO
is a in-memory stream for text.

Argument names are not part of the specification, and only the arguments
of open() are intended to be used as keyword arguments.



   An int containing the default buffer size used by the module's buffered
   I/O classes. open() uses the file's blksize (as obtained by os.stat) if
# New I/O library conforming to PEP 3116.

# XXX edge cases when switching between reading/writing
# XXX need to support 1 meaning line-buffered
# XXX whenever an argument is None, use the default value
# XXX read/write ops should check readable/writable
# XXX buffered readinto should work with arbitrary buffer objects
# XXX use incremental encoder for text output, at least for UTF-16 and UTF-8-SIG
# XXX check writable, readable and seekable in appropriate places

__author__ = ("Guido van Rossum <>, "
              "Mike Verdone <>, "
              "Mark Russell <>, "
              "Antoine Pitrou <>, "
              "Amaury Forgeot d'Arc <>, "
              "Benjamin Peterson <>")

__all__ = ["BlockingIOError", "open", "IOBase", "RawIOBase", "FileIO",
           "BytesIO", "StringIO", "BufferedIOBase",
           "BufferedReader", "BufferedWriter", "BufferedRWPair",
           "BufferedRandom", "TextIOBase", "TextIOWrapper",
           "UnsupportedOperation", "SEEK_SET", "SEEK_CUR", "SEEK_END"]

import _io
import abc

from _io import (DEFAULT_BUFFER_SIZE, BlockingIOError, UnsupportedOperation,
                 open, FileIO, BytesIO, StringIO, BufferedReader,
                 BufferedWriter, BufferedRWPair, BufferedRandom,
                 IncrementalNewlineDecoder, TextIOWrapper)

OpenWrapper = # for compatibility with _pyio

# for seek()

# Declaring ABCs in C is tricky so we do it here.
# Method descriptions and default implementations are inherited from the C
# version however.
class IOBase(_io._IOBase):
    __metaclass__ = abc.ABCMeta

class RawIOBase(_io._RawIOBase, IOBase):

class BufferedIOBase(_io._BufferedIOBase, IOBase):

class TextIOBase(_io._TextIOBase, IOBase):


for klass in (BytesIO, BufferedReader, BufferedWriter, BufferedRandom,

for klass in (StringIO, TextIOWrapper):
del klass