"io" --- Core tools for working with streams
********************************************

**Code source:** Lib/io.py

======================================================================


Aperçu
======

The "io" module provides Python's main facilities for dealing with
various types of I/O.  There are three main types of I/O: *text I/O*,
*binary I/O* and *raw I/O*.  These are generic categories, and various
backing stores can be used for each of them.  A concrete object
belonging to any of these categories is called a *file object*.  Other
common terms are *stream* and *file-like object*.

Independent of its category, each concrete stream object will also
have various capabilities: it can be read-only, write-only, or read-
write. It can also allow arbitrary random access (seeking forwards or
backwards to any location), or only sequential access (for example in
the case of a socket or pipe).

All streams are careful about the type of data you give to them.  For
example giving a "str" object to the "write()" method of a binary
stream will raise a "TypeError".  So will giving a "bytes" object to
the "write()" method of a text stream.

Modifié dans la version 3.3: Operations that used to raise "IOError"
now raise "OSError", since "IOError" is now an alias of "OSError".


Entrée/sortie de texte
----------------------

Text I/O expects and produces "str" objects.  This means that whenever
the backing store is natively made of bytes (such as in the case of a
file), encoding and decoding of data is made transparently as well as
optional translation of platform-specific newline characters.

The easiest way to create a text stream is with "open()", optionally
specifying an encoding:

   f = open("myfile.txt", "r", encoding="utf-8")

Les flux de texte en mémoire sont également disponible sous forme
d'objets "StringIO" :

   f = io.StringIO("some initial text data")

L'API de flux textuel est décrite en détail dans la documentation de
la classe "TextIOBase".


Binary I/O
----------

Binary I/O (also called *buffered I/O*) expects *bytes-like objects*
and produces "bytes" objects.  No encoding, decoding, or newline
translation is performed.  This category of streams can be used for
all kinds of non-text data, and also when manual control over the
handling of text data is desired.

The easiest way to create a binary stream is with "open()" with "'b'"
in the mode string:

   f = open("myfile.jpg", "rb")

Les flux de texte en mémoire sont également disponible sous forme
d'objets "BytesIO" :

   f = io.BytesIO(b"some initial binary data: \x00\x01")

L'API du flux binaire est décrite en détail dans la documentation de
la classe "BufferedIOBase".

D'autres bibliothèques peuvent fournir des moyens supplémentaires pour
créer des flux de texte ou flux binaire. Voir la méthode
"socket.socket.makefile()" par exemple.


Raw I/O
-------

Raw I/O (also called *unbuffered I/O*) is generally used as a low-
level building-block for binary and text streams; it is rarely useful
to directly manipulate a raw stream from user code.  Nevertheless, you
can create a raw stream by opening a file in binary mode with
buffering disabled:

   f = open("myfile.jpg", "rb", buffering=0)

The raw stream API is described in detail in the docs of "RawIOBase".


Encodage de texte
=================

The default encoding of "TextIOWrapper" and "open()" is locale-
specific ("locale.getencoding()").

However, many developers forget to specify the encoding when opening
text files encoded in UTF-8 (e.g. JSON, TOML, Markdown, etc...) since
most Unix platforms use UTF-8 locale by default. This causes bugs
because the locale encoding is not UTF-8 for most Windows users. For
example:

   # May not work on Windows when non-ASCII characters in the file.
   with open("README.md") as f:
       long_description = f.read()

Accordingly, it is highly recommended that you specify the encoding
explicitly when opening text files. If you want to use UTF-8, pass
"encoding="utf-8"". To use the current locale encoding,
"encoding="locale"" is supported since Python 3.10.

Voir aussi:

  Le mode UTF-8 de Python
     Le mode UTF-8 de Python peut être utilisé pour changer l'encodage
     par défaut en UTF-8 à partir d'un encodage local spécifique.

  **PEP 686**
     Le mode UTF-8 de Python sera par mis par défaut sur Python 3.15.


Opt-in EncodingWarning
----------------------

Ajouté dans la version 3.10: See **PEP 597** for more details.

To find where the default locale encoding is used, you can enable the
"-X warn_default_encoding" command line option or set the
"PYTHONWARNDEFAULTENCODING" environment variable, which will emit an
"EncodingWarning" when the default encoding is used.

If you are providing an API that uses "open()" or "TextIOWrapper" and
passes "encoding=None" as a parameter, you can use "text_encoding()"
so that callers of the API will emit an "EncodingWarning" if they
don't pass an "encoding". However, please consider using UTF-8 by
default (i.e. "encoding="utf-8"") for new APIs.


Interface de haut niveau du module
==================================

io.DEFAULT_BUFFER_SIZE

   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 possible.

io.open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True, opener=None)

   This is an alias for the builtin "open()" function.

   This function raises an auditing event "open" with arguments
   *path*, *mode* and *flags*. The *mode* and *flags* arguments may
   have been modified or inferred from the original call.

io.open_code(path)

   Opens the provided file with mode "'rb'". This function should be
   used when the intent is to treat the contents as executable code.

   *path* should be a "str" and an absolute path.

   The behavior of this function may be overridden by an earlier call
   to the "PyFile_SetOpenCodeHook()". However, assuming that *path* is
   a "str" and an absolute path, "open_code(path)" should always
   behave the same as "open(path, 'rb')". Overriding the behavior is
   intended for additional validation or preprocessing of the file.

   Ajouté dans la version 3.8.

io.text_encoding(encoding, stacklevel=2, /)

   This is a helper function for callables that use "open()" or
   "TextIOWrapper" and have an "encoding=None" parameter.

   This function returns *encoding* if it is not "None". Otherwise, it
   returns ""locale"" or ""utf-8"" depending on UTF-8 Mode.

   This function emits an "EncodingWarning" if
   "sys.flags.warn_default_encoding" is true and *encoding* is "None".
   *stacklevel* specifies where the warning is emitted. For example:

      def read_text(path, encoding=None):
          encoding = io.text_encoding(encoding)  # stacklevel=2
          with open(path, encoding) as f:
              return f.read()

   In this example, an "EncodingWarning" is emitted for the caller of
   "read_text()".

   Voir Encodage de texte pour plus d'informations.

   Ajouté dans la version 3.10.

   Modifié dans la version 3.11: "text_encoding()" returns "utf-8"
   when UTF-8 mode is enabled and *encoding* is "None".

exception io.BlockingIOError

   This is a compatibility alias for the builtin "BlockingIOError"
   exception.

exception io.UnsupportedOperation

   An exception inheriting "OSError" and "ValueError" that is raised
   when an unsupported operation is called on a stream.

Voir aussi:

  "sys"
     contains the standard IO streams: "sys.stdin", "sys.stdout", and
     "sys.stderr".


Class hierarchy
===============

The implementation of I/O streams is organized as a hierarchy of
classes.  First *abstract base classes* (ABCs), which are used to
specify the various categories of streams, then concrete classes
providing the standard stream implementations.

Note:

  The abstract base classes also provide default implementations of
  some methods in order to help implementation of concrete stream
  classes.  For example, "BufferedIOBase" provides unoptimized
  implementations of "readinto()" and "readline()".

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 raise "UnsupportedOperation" if they do
not support a given operation.

The "RawIOBase" ABC extends "IOBase".  It deals with the reading and
writing of bytes to a stream.  "FileIO" subclasses "RawIOBase" to
provide an interface to files in the machine's file system.

The "BufferedIOBase" ABC extends "IOBase".  It deals with buffering on
a raw binary stream ("RawIOBase").  Its subclasses, "BufferedWriter",
"BufferedReader", and "BufferedRWPair" buffer raw binary streams that
are writable, readable, and both readable and writable, respectively.
"BufferedRandom" provides a buffered interface to seekable streams.
Another "BufferedIOBase" subclass, "BytesIO", is a stream of in-memory
bytes.

The "TextIOBase" ABC extends "IOBase".  It deals with streams whose
bytes represent text, and handles encoding and decoding to and from
strings.  "TextIOWrapper", which extends "TextIOBase", is a buffered
text interface to a buffered raw stream ("BufferedIOBase").  Finally,
"StringIO" is an 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.

The following table summarizes the ABCs provided by the "io" module:

+---------------------------+--------------------+--------------------------+----------------------------------------------------+
| ABC                       | Inherits           | Stub Methods             | Méthodes et propriétés de Mixin                    |
|===========================|====================|==========================|====================================================|
| "IOBase"                  |                    | "fileno", "seek", et     | "close", "closed", "__enter__", "__exit__",        |
|                           |                    | "truncate"               | "flush", "isatty", "__iter__", "__next__",         |
|                           |                    |                          | "readable", "readline", "readlines", "seekable",   |
|                           |                    |                          | "tell", "writable", and "writelines"               |
+---------------------------+--------------------+--------------------------+----------------------------------------------------+
| "RawIOBase"               | "IOBase"           | "readinto" et "write"    | Inherited "IOBase" methods, "read", and "readall"  |
+---------------------------+--------------------+--------------------------+----------------------------------------------------+
| "BufferedIOBase"          | "IOBase"           | "detach", "read",        | Inherited "IOBase" methods, "readinto", and        |
|                           |                    | "read1", et "write"      | "readinto1"                                        |
+---------------------------+--------------------+--------------------------+----------------------------------------------------+
| "TextIOBase"              | "IOBase"           | "detach", "read",        | Inherited "IOBase" methods, "encoding", "errors",  |
|                           |                    | "readline", et "write"   | and "newlines"                                     |
+---------------------------+--------------------+--------------------------+----------------------------------------------------+


I/O Base Classes
----------------

class io.IOBase

   The abstract base class for all I/O classes.

   This class provides empty abstract implementations for many methods
   that derived classes can override selectively; the default
   implementations represent a file that cannot be read, written or
   seeked.

   Even though "IOBase" does not declare "read()" or "write()" because
   their signatures will vary, implementations and clients should
   consider those methods part of the interface.  Also,
   implementations may raise a "ValueError" (or
   "UnsupportedOperation") when operations they do not support are
   called.

   The basic type used for binary data read from or written to a file
   is "bytes".  Other *bytes-like objects* are accepted as method
   arguments too.  Text I/O classes work with "str" data.

   Note that calling any method (even inquiries) on a closed stream is
   undefined.  Implementations may raise "ValueError" in this case.

   "IOBase" (and its subclasses) supports the iterator protocol,
   meaning that an "IOBase" object can be iterated over yielding the
   lines in a stream.  Lines are defined slightly differently
   depending on whether the stream is a binary stream (yielding
   bytes), or a text stream (yielding character strings).  See
   "readline()" below.

   "IOBase" is also a context manager and therefore supports the
   "with" statement.  In this example, *file* is closed after the
   "with" statement's suite is finished---even if an exception occurs:

      with open('spam.txt', 'w') as file:
          file.write('Spam and eggs!')

   "IOBase" provides these data attributes and methods:

   close()

      Flush and close this stream. This method has no effect if the
      file is already closed. Once the file is closed, any operation
      on the file (e.g. reading or writing) will raise a "ValueError".

      As a convenience, it is allowed to call this method more than
      once; only the first call, however, will have an effect.

   closed

      "True" if the stream is closed.

   fileno()

      Return the underlying file descriptor (an integer) of the stream
      if it exists.  An "OSError" is raised if the IO object does not
      use a file descriptor.

   flush()

      Flush the write buffers of the stream if applicable.  This does
      nothing for read-only and non-blocking streams.

   isatty()

      Return "True" if the stream is interactive (i.e., connected to a
      terminal/tty device).

   readable()

      Return "True" if the stream can be read from. If "False",
      "read()" will raise "OSError".

   readline(size=-1, /)

      Read and return one line from the stream.  If *size* is
      specified, at most *size* bytes will be read.

      The line terminator is always "b'\n'" for binary files; for text
      files, the *newline* argument to "open()" can be used to select
      the line terminator(s) recognized.

   readlines(hint=-1, /)

      Read and return a list of lines from the stream.  *hint* can be
      specified to control the number of lines read: no more lines
      will be read if the total size (in bytes/characters) of all
      lines so far exceeds *hint*.

      *hint* values of "0" or less, as well as "None", are treated as
      no hint.

      Note that it's already possible to iterate on file objects using
      "for line in file: ..." without calling "file.readlines()".

   seek(offset, whence=os.SEEK_SET, /)

      Change the stream position to the given byte *offset*,
      interpreted relative to the position indicated by *whence*, and
      return the new absolute position. Values for *whence* are:

      * "os.SEEK_SET" or "0" -- start of the stream (the default);
        *offset* should be zero or positive

      * "os.SEEK_CUR" or "1" -- current stream position; *offset* may
        be negative

      * "os.SEEK_END" or "2" -- end of the stream; *offset* is usually
        negative

      Ajouté dans la version 3.1: The "SEEK_*" constants.

      Ajouté dans la version 3.3: Some operating systems could support
      additional values, like "os.SEEK_HOLE" or "os.SEEK_DATA". The
      valid values for a file could depend on it being open in text or
      binary mode.

   seekable()

      Return "True" if the stream supports random access.  If "False",
      "seek()", "tell()" and "truncate()" will raise "OSError".

   tell()

      Return the current stream position.

   truncate(size=None, /)

      Resize the stream to the given *size* in bytes (or the current
      position if *size* is not specified).  The current stream
      position isn't changed. This resizing can extend or reduce the
      current file size.  In case of extension, the contents of the
      new file area depend on the platform (on most systems,
      additional bytes are zero-filled).  The new file size is
      returned.

      Modifié dans la version 3.5: Windows will now zero-fill files
      when extending.

   writable()

      Return "True" if the stream supports writing.  If "False",
      "write()" and "truncate()" will raise "OSError".

   writelines(lines, /)

      Write a list of lines to the stream.  Line separators are not
      added, so it is usual for each of the lines provided to have a
      line separator at the end.

   __del__()

      Prepare for object destruction. "IOBase" provides a default
      implementation of this method that calls the instance's
      "close()" method.

class io.RawIOBase

   Base class for raw binary streams.  It inherits from "IOBase".

   Raw binary streams typically provide low-level access to an
   underlying OS device or API, and do not try to encapsulate it in
   high-level primitives (this functionality is done at a higher-level
   in buffered binary streams and text streams, described later in
   this page).

   "RawIOBase" provides these methods in addition to those from
   "IOBase":

   read(size=-1, /)

      Read up to *size* bytes from the object and return them.  As a
      convenience, if *size* is unspecified or -1, all bytes until EOF
      are returned. Otherwise, only one system call is ever made.
      Fewer than *size* bytes may be returned if the operating system
      call returns fewer than *size* bytes.

      If 0 bytes are returned, and *size* was not 0, this indicates
      end of file. If the object is in non-blocking mode and no bytes
      are available, "None" is returned.

      The default implementation defers to "readall()" and
      "readinto()".

   readall()

      Read and return all the bytes from the stream until EOF, using
      multiple calls to the stream if necessary.

   readinto(b, /)

      Read bytes into a pre-allocated, writable *bytes-like object*
      *b*, and return the number of bytes read.  For example, *b*
      might be a "bytearray". If the object is in non-blocking mode
      and no bytes are available, "None" is returned.

   write(b, /)

      Write the given *bytes-like object*, *b*, to the underlying raw
      stream, and return the number of bytes written.  This can be
      less than the length of *b* in bytes, depending on specifics of
      the underlying raw stream, and especially if it is in non-
      blocking mode.  "None" is returned if the raw stream is set not
      to block and no single byte could be readily written to it.  The
      caller may release or mutate *b* after this method returns, so
      the implementation should only access *b* during the method
      call.

class io.BufferedIOBase

   Base class for binary streams that support some kind of buffering.
   It inherits from "IOBase".

   The main difference with "RawIOBase" is that methods "read()",
   "readinto()" and "write()" will try (respectively) to read as much
   input as requested or to emit all provided data.

   In addition, if the underlying raw stream is in non-blocking mode,
   when the system returns would block "write()" will raise
   "BlockingIOError" with "BlockingIOError.characters_written" and
   "read()" will return data read so far or "None" if no data is
   available.

   Besides, the "read()" method does not have a default implementation
   that defers to "readinto()".

   A typical "BufferedIOBase" implementation should not inherit from a
   "RawIOBase" implementation, but wrap one, like "BufferedWriter" and
   "BufferedReader" do.

   "BufferedIOBase" provides or overrides these data attributes and
   methods in addition to those from "IOBase":

   raw

      The underlying raw stream (a "RawIOBase" instance) that
      "BufferedIOBase" deals with.  This is not part of the
      "BufferedIOBase" API and may not exist on some implementations.

   detach()

      Sépare le flux brut sous-jacent du tampon et le renvoie.

      After the raw stream has been detached, the buffer is in an
      unusable state.

      Some buffers, like "BytesIO", do not have the concept of a
      single raw stream to return from this method.  They raise
      "UnsupportedOperation".

      Ajouté dans la version 3.1.

   read(size=-1, /)

      Read and return up to *size* bytes. If the argument is omitted,
      "None", or negative read as much as possible.

      Fewer bytes may be returned than requested. An empty "bytes"
      object is returned if the stream is already at EOF. More than
      one read may be made and calls may be retried if specific errors
      are encountered, see "os.read()" and **PEP 475** for more
      details. Less than size bytes being returned does not imply that
      EOF is imminent.

      When reading as much as possible the default implementation will
      use "raw.readall" if available (which should implement
      "RawIOBase.readall()"), otherwise will read in a loop until read
      returns "None", an empty "bytes", or a non-retryable error. For
      most streams this is to EOF, but for non-blocking streams more
      data may become available.

      Note:

        When the underlying raw stream is non-blocking,
        implementations may either raise "BlockingIOError" or return
        "None" if no data is available. "io" implementations return
        "None".

   read1(size=-1, /)

      Read and return up to *size* bytes, calling "readinto()" which
      may retry if "EINTR" is encountered per **PEP 475**. If *size*
      is "-1" or not provided, the implementation will choose an
      arbitrary value for *size*.

      Note:

        When the underlying raw stream is non-blocking,
        implementations may either raise "BlockingIOError" or return
        "None" if no data is available. "io" implementations return
        "None".

   readinto(b, /)

      Read bytes into a pre-allocated, writable *bytes-like object*
      *b* and return the number of bytes read. For example, *b* might
      be a "bytearray".

      Like "read()", multiple reads may be issued to the underlying
      raw stream, unless the latter is interactive.

      A "BlockingIOError" is raised if the underlying raw stream is in
      non blocking-mode, and has no data available at the moment.

   readinto1(b, /)

      Read bytes into a pre-allocated, writable *bytes-like object*
      *b*, using at most one call to the underlying raw stream's
      "read()" (or "readinto()") method. Return the number of bytes
      read.

      A "BlockingIOError" is raised if the underlying raw stream is in
      non blocking-mode, and has no data available at the moment.

      Ajouté dans la version 3.5.

   write(b, /)

      Write the given *bytes-like object*, *b*, and return the number
      of bytes written (always equal to the length of *b* in bytes,
      since if the write fails an "OSError" will be raised).
      Depending on the actual implementation, these bytes may be
      readily written to the underlying stream, or held in a buffer
      for performance and latency reasons.

      When in non-blocking mode, a "BlockingIOError" is raised if the
      data needed to be written to the raw stream but it couldn't
      accept all the data without blocking.

      The caller may release or mutate *b* after this method returns,
      so the implementation should only access *b* during the method
      call.


Raw File I/O
------------

class io.FileIO(name, mode='r', closefd=True, opener=None)

   A raw binary stream representing an OS-level file containing bytes
   data.  It inherits from "RawIOBase".

   The *name* can be one of two things:

   * a character string or "bytes" object representing the path to the
     file which will be opened. In this case closefd must be "True"
     (the default) otherwise an error will be raised.

   * an integer representing the number of an existing OS-level file
     descriptor to which the resulting "FileIO" object will give
     access. When the FileIO object is closed this fd will be closed
     as well, unless *closefd* is set to "False".

   The *mode* can be "'r'", "'w'", "'x'" or "'a'" for reading
   (default), writing, exclusive creation or appending. The file will
   be created if it doesn't exist when opened for writing or
   appending; it will be truncated when opened for writing.
   "FileExistsError" will be raised if it already exists when opened
   for creating. Opening a file for creating implies writing, so this
   mode behaves in a similar way to "'w'". Add a "'+'" to the mode to
   allow simultaneous reading and writing.

   The "read()" (when called with a positive argument), "readinto()"
   and "write()" methods on this class will only make one system call.

   Un *opener* personnalisé peut être utilisé en fournissant un
   appelable à *opener*. Le descripteur de fichier de cet objet
   fichier sera alors obtenu en appelant *opener* avec (*file*,
   *flags*). *opener* doit donner un descripteur de fichier ouvert
   (fournir "os.open" en temps qu'*opener* aura le même effet que
   donner "None").

   Il n'est pas possible d'hériter du fichier nouvellement créé.

   See the "open()" built-in function for examples on using the
   *opener* parameter.

   Modifié dans la version 3.3: The *opener* parameter was added. The
   "'x'" mode was added.

   Modifié dans la version 3.4: Il n'est plus possible d'hériter de
   *file*.

   "FileIO" provides these data attributes in addition to those from
   "RawIOBase" and "IOBase":

   mode

      The mode as given in the constructor.

   name

      Le nom du fichier. C'est le descripteur du fichier lorsqu'aucun
      nom n'est donné dans le constructeur.


Buffered Streams
----------------

Buffered I/O streams provide a higher-level interface to an I/O device
than raw I/O does.

class io.BytesIO(initial_bytes=b'')

   A binary stream using an in-memory bytes buffer.  It inherits from
   "BufferedIOBase".  The buffer is discarded when the "close()"
   method is called.

   The optional argument *initial_bytes* is a *bytes-like object* that
   contains initial data.

   "BytesIO" provides or overrides these methods in addition to those
   from "BufferedIOBase" and "IOBase":

   getbuffer()

      Return a readable and writable view over the contents of the
      buffer without copying them.  Also, mutating the view will
      transparently update the contents of the buffer:

         >>> b = io.BytesIO(b"abcdef")
         >>> view = b.getbuffer()
         >>> view[2:4] = b"56"
         >>> b.getvalue()
         b'ab56ef'

      Note:

        As long as the view exists, the "BytesIO" object cannot be
        resized or closed.

      Ajouté dans la version 3.2.

   getvalue()

      Return "bytes" containing the entire contents of the buffer.

   read1(size=-1, /)

      In "BytesIO", this is the same as "read()".

      Modifié dans la version 3.7: The *size* argument is now
      optional.

   readinto1(b, /)

      In "BytesIO", this is the same as "readinto()".

      Ajouté dans la version 3.5.

class io.BufferedReader(raw, buffer_size=DEFAULT_BUFFER_SIZE)

   A buffered binary stream providing higher-level access to a
   readable, non seekable "RawIOBase" raw binary stream.  It inherits
   from "BufferedIOBase".

   When reading data from this object, a larger amount of data may be
   requested from the underlying raw stream, and kept in an internal
   buffer. The buffered data can then be returned directly on
   subsequent reads.

   The constructor creates a "BufferedReader" for the given readable
   *raw* stream and *buffer_size*.  If *buffer_size* is omitted,
   "DEFAULT_BUFFER_SIZE" is used.

   "BufferedReader" provides or overrides these methods in addition to
   those from "BufferedIOBase" and "IOBase":

   peek(size=0, /)

      Return bytes from the stream without advancing the position. The
      number of bytes returned may be less or more than requested. If
      the underlying raw stream is non-blocking and the operation
      would block, returns empty bytes.

   read(size=-1, /)

      In "BufferedReader" this is the same as
      "io.BufferedIOBase.read()"

   read1(size=-1, /)

      In "BufferedReader" this is the same as
      "io.BufferedIOBase.read1()"

      Modifié dans la version 3.7: The *size* argument is now
      optional.

class io.BufferedWriter(raw, buffer_size=DEFAULT_BUFFER_SIZE)

   A buffered binary stream providing higher-level access to a
   writeable, non seekable "RawIOBase" raw binary stream.  It inherits
   from "BufferedIOBase".

   When writing to this object, data is normally placed into an
   internal buffer.  The buffer will be written out to the underlying
   "RawIOBase" object under various conditions, including:

   * when the buffer gets too small for all pending data;

   * when "flush()" is called;

   * when a "seek()" is requested (for "BufferedRandom" objects);

   * when the "BufferedWriter" object is closed or destroyed.

   The constructor creates a "BufferedWriter" for the given writeable
   *raw* stream.  If the *buffer_size* is not given, it defaults to
   "DEFAULT_BUFFER_SIZE".

   "BufferedWriter" provides or overrides these methods in addition to
   those from "BufferedIOBase" and "IOBase":

   flush()

      Force bytes held in the buffer into the raw stream.  A
      "BlockingIOError" should be raised if the raw stream blocks.

   write(b, /)

      Write the *bytes-like object*, *b*, and return the number of
      bytes written.  When in non-blocking mode, a "BlockingIOError"
      with "BlockingIOError.characters_written" set is raised if the
      buffer needs to be written out but the raw stream blocks.

class io.BufferedRandom(raw, buffer_size=DEFAULT_BUFFER_SIZE)

   A buffered binary stream providing higher-level access to a
   seekable "RawIOBase" raw binary stream.  It inherits from
   "BufferedReader" and "BufferedWriter".

   The constructor creates a reader and writer for a seekable raw
   stream, given in the first argument.  If the *buffer_size* is
   omitted it defaults to "DEFAULT_BUFFER_SIZE".

   "BufferedRandom" is capable of anything "BufferedReader" or
   "BufferedWriter" can do.  In addition, "seek()" and "tell()" are
   guaranteed to be implemented.

class io.BufferedRWPair(reader, writer, buffer_size=DEFAULT_BUFFER_SIZE, /)

   A buffered binary stream providing higher-level access to two non
   seekable "RawIOBase" raw binary streams---one readable, the other
   writeable. It inherits from "BufferedIOBase".

   *reader* and *writer* are "RawIOBase" objects that are readable and
   writeable respectively.  If the *buffer_size* is omitted it
   defaults to "DEFAULT_BUFFER_SIZE".

   "BufferedRWPair" implements all of "BufferedIOBase"'s methods
   except for "detach()", which raises "UnsupportedOperation".

   Avertissement:

     "BufferedRWPair" does not attempt to synchronize accesses to its
     underlying raw streams.  You should not pass it the same object
     as reader and writer; use "BufferedRandom" instead.


Entrée/sortie de texte
----------------------

class io.TextIOBase

   Base class for text streams.  This class provides a character and
   line based interface to stream I/O.  It inherits from "IOBase".

   "TextIOBase" provides or overrides these data attributes and
   methods in addition to those from "IOBase":

   encoding

      The name of the encoding used to decode the stream's bytes into
      strings, and to encode strings into bytes.

   errors

      The error setting of the decoder or encoder.

   newlines

      A string, a tuple of strings, or "None", indicating the newlines
      translated so far.  Depending on the implementation and the
      initial constructor flags, this may not be available.

   buffer

      The underlying binary buffer (a "BufferedIOBase" or "RawIOBase"
      instance) that "TextIOBase" deals with. This is not part of the
      "TextIOBase" API and may not exist in some implementations.

   detach()

      Separate the underlying binary buffer from the "TextIOBase" and
      return it.

      After the underlying buffer has been detached, the "TextIOBase"
      is in an unusable state.

      Some "TextIOBase" implementations, like "StringIO", may not have
      the concept of an underlying buffer and calling this method will
      raise "UnsupportedOperation".

      Ajouté dans la version 3.1.

   read(size=-1, /)

      Read and return at most *size* characters from the stream as a
      single "str".  If *size* is negative or "None", reads until EOF.

   readline(size=-1, /)

      Read until newline or EOF and return a single "str".  If the
      stream is already at EOF, an empty string is returned.

      If *size* is specified, at most *size* characters will be read.

   seek(offset, whence=SEEK_SET, /)

      Change the stream position to the given *offset*.  Behaviour
      depends on the *whence* parameter.  The default value for
      *whence* is "SEEK_SET".

      * "SEEK_SET" or "0": seek from the start of the stream (the
        default); *offset* must either be a number returned by
        "TextIOBase.tell()", or zero.  Any other *offset* value
        produces undefined behaviour.

      * "SEEK_CUR" or "1": "seek" to the current position; *offset*
        must be zero, which is a no-operation (all other values are
        unsupported).

      * "SEEK_END" or "2": seek to the end of the stream; *offset*
        must be zero (all other values are unsupported).

      Return the new absolute position as an opaque number.

      Ajouté dans la version 3.1: The "SEEK_*" constants.

   tell()

      Return the current stream position as an opaque number.  The
      number does not usually represent a number of bytes in the
      underlying binary storage.

   write(s, /)

      Write the string *s* to the stream and return the number of
      characters written.

class io.TextIOWrapper(buffer, encoding=None, errors=None, newline=None, line_buffering=False, write_through=False)

   A buffered text stream providing higher-level access to a
   "BufferedIOBase" buffered binary stream.  It inherits from
   "TextIOBase".

   *encoding* gives the name of the encoding that the stream will be
   decoded or encoded with.  In UTF-8 Mode, this defaults to UTF-8.
   Otherwise, it defaults to "locale.getencoding()".
   "encoding="locale"" can be used to specify the current locale's
   encoding explicitly. See Encodage de texte for more information.

   *errors* is an optional string that specifies how encoding and
   decoding errors are to be handled.  Pass "'strict'" to raise a
   "ValueError" exception if there is an encoding error (the default
   of "None" has the same effect), or pass "'ignore'" to ignore
   errors.  (Note that ignoring encoding errors can lead to data
   loss.)  "'replace'" causes a replacement marker (such as "'?'") to
   be inserted where there is malformed data. "'backslashreplace'"
   causes malformed data to be replaced by a backslashed escape
   sequence.  When writing, "'xmlcharrefreplace'" (replace with the
   appropriate XML character reference)  or "'namereplace'" (replace
   with "\N{...}" escape sequences) can be used.  Any other error
   handling name that has been registered with
   "codecs.register_error()" is also valid.

   *newline* controls how line endings are handled.  It can be "None",
   "''", "'\n'", "'\r'", and "'\r\n'".  It works as follows:

   * When reading input from the stream, if *newline* is "None",
     *universal newlines* mode is enabled.  Lines in the input can end
     in "'\n'", "'\r'", or "'\r\n'", and these are translated into
     "'\n'" before being returned to the caller.  If *newline* is
     "''", universal newlines mode is enabled, but line endings are
     returned to the caller untranslated.  If *newline* has any of the
     other legal values, input lines are only terminated by the given
     string, and the line ending is returned to the caller
     untranslated.

   * Lors de l'écriture, si *newline* est "None", chaque "'\n'" est
     remplacé par le séparateur de lignes par défaut du système
     "os.linesep".  Si *newline* est "*" ou "'\n'" aucun remplacent
     n'est effectué. Si *newline* est un autre caractère valide,
     chaque "'\n'" sera remplacé par la chaîne donnée.

   If *line_buffering* is "True", "flush()" is implied when a call to
   write contains a newline character or a carriage return.

   If *write_through* is "True", calls to "write()" are guaranteed not
   to be buffered: any data written on the "TextIOWrapper" object is
   immediately handled to its underlying binary *buffer*.

   Modifié dans la version 3.3: Le paramètre *write_through* a été
   ajouté.

   Modifié dans la version 3.3: The default *encoding* is now
   "locale.getpreferredencoding(False)" instead of
   "locale.getpreferredencoding()". Don't change temporary the locale
   encoding using "locale.setlocale()", use the current locale
   encoding instead of the user preferred encoding.

   Modifié dans la version 3.10: The *encoding* argument now supports
   the ""locale"" dummy encoding name.

   "TextIOWrapper" provides these data attributes and methods in
   addition to those from "TextIOBase" and "IOBase":

   line_buffering

      Whether line buffering is enabled.

   write_through

      Whether writes are passed immediately to the underlying binary
      buffer.

      Ajouté dans la version 3.7.

   reconfigure(*, encoding=None, errors=None, newline=None, line_buffering=None, write_through=None)

      Reconfigure this text stream using new settings for *encoding*,
      *errors*, *newline*, *line_buffering* and *write_through*.

      Parameters not specified keep current settings, except
      "errors='strict'" is used when *encoding* is specified but
      *errors* is not specified.

      Il n'est pas possible de modifier l'encodage ou une nouvelle
      ligne si des données ont déjà été lues à partir du flux. En
      revanche, il est possible de modifier l'encodage après
      l'écriture.

      Cette méthode effectue un nettoyage implicite du flux avant de
      définir les nouveaux paramètres.

      Ajouté dans la version 3.7.

      Modifié dans la version 3.11: La méthode prend en charge
      l'option "encoding="locale"".

   seek(cookie, whence=os.SEEK_SET, /)

      Set the stream position. Return the new stream position as an
      "int".

      Four operations are supported, given by the following argument
      combinations:

      * "seek(0, SEEK_SET)": Rewind to the start of the stream.

      * "seek(cookie, SEEK_SET)": Restore a previous position;
        *cookie* **must be** a number returned by "tell()".

      * "seek(0, SEEK_END)": Fast-forward to the end of the stream.

      * "seek(0, SEEK_CUR)": Leave the current stream position
        unchanged.

      Any other argument combinations are invalid, and may raise
      exceptions.

      Voir aussi: "os.SEEK_SET", "os.SEEK_CUR", and "os.SEEK_END".

   tell()

      Return the stream position as an opaque number. The return value
      of "tell()" can be given as input to "seek()", to restore a
      previous stream position.

class io.StringIO(initial_value='', newline='\n')

   A text stream using an in-memory text buffer.  It inherits from
   "TextIOBase".

   The text buffer is discarded when the "close()" method is called.

   The initial value of the buffer can be set by providing
   *initial_value*. If newline translation is enabled, newlines will
   be encoded as if by "write()".  The stream is positioned at the
   start of the buffer which emulates opening an existing file in a
   "w+" mode, making it ready for an immediate write from the
   beginning or for a write that would overwrite the initial value.
   To emulate opening a file in an "a+" mode ready for appending, use
   "f.seek(0, io.SEEK_END)" to reposition the stream at the end of the
   buffer.

   The *newline* argument works like that of "TextIOWrapper", except
   that when writing output to the stream, if *newline* is "None",
   newlines are written as "\n" on all platforms.

   "StringIO" provides this method in addition to those from
   "TextIOBase" and "IOBase":

   getvalue()

      Return a "str" containing the entire contents of the buffer.
      Newlines are decoded as if by "read()", although the stream
      position is not changed.

   Exemple d'utilisation :

      import io

      output = io.StringIO()
      output.write('First line.\n')
      print('Second line.', file=output)

      # Retrieve file contents -- this will be
      # 'First line.\nSecond line.\n'
      contents = output.getvalue()

      # Close object and discard memory buffer --
      # .getvalue() will now raise an exception.
      output.close()

class io.IncrementalNewlineDecoder

   A helper codec that decodes newlines for *universal newlines* mode.
   It inherits from "codecs.IncrementalDecoder".


Performances
============

Cette section aborde les performances des implémentations concrètes
d'Entrée/Sortie fournies.


Binary I/O
----------

By reading and writing only large chunks of data even when the user
asks for a single byte, buffered I/O hides any inefficiency in calling
and executing the operating system's unbuffered I/O routines.  The
gain depends on the OS and the kind of I/O which is performed.  For
example, on some modern OSes such as Linux, unbuffered disk I/O can be
as fast as buffered I/O.  The bottom line, however, is that buffered
I/O offers predictable performance regardless of the platform and the
backing device.  Therefore, it is almost always preferable to use
buffered I/O rather than unbuffered I/O for binary data.


Entrée/sortie de texte
----------------------

Text I/O over a binary storage (such as a file) is significantly
slower than binary I/O over the same storage, because it requires
conversions between unicode and binary data using a character codec.
This can become noticeable handling huge amounts of text data like
large log files.  Also, "tell()" and "seek()" are both quite slow due
to the reconstruction algorithm used.

"StringIO", however, is a native in-memory unicode container and will
exhibit similar speed to "BytesIO".


Fils d'exécution
----------------

"FileIO" objects are thread-safe to the extent that the operating
system calls (such as *read(2)* under Unix) they wrap are thread-safe
too.

Binary buffered objects (instances of "BufferedReader",
"BufferedWriter", "BufferedRandom" and "BufferedRWPair") protect their
internal structures using a lock; it is therefore safe to call them
from multiple threads at once.

les objets "TextIOWrapper" ne sont pas compatibles avec les programmes
à fils d'exécutions multiples.


Réentrance
----------

Binary buffered objects (instances of "BufferedReader",
"BufferedWriter", "BufferedRandom" and "BufferedRWPair") are not
reentrant.  While reentrant calls will not happen in normal
situations, they can arise from doing I/O in a "signal" handler.  If a
thread tries to re-enter a buffered object which it is already
accessing, a "RuntimeError" is raised.  Note this doesn't prohibit a
different thread from entering the buffered object.

The above implicitly extends to text files, since the "open()"
function will wrap a buffered object inside a "TextIOWrapper".  This
includes standard streams and therefore affects the built-in "print()"
function as well.
