"readline" --- GNU readline interface
*************************************

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

The "readline" module defines a number of functions to facilitate
completion and reading/writing of history files from the Python
interpreter. This module can be used directly, or via the
"rlcompleter" module, which supports completion of Python identifiers
at the interactive prompt.  Settings made using  this module affect
the behaviour of both the interpreter's interactive prompt  and the
prompts offered by the built-in "input()" function.

Readline keybindings may be configured via an initialization file,
typically ".inputrc" in your home directory.  See Readline Init File
in the GNU Readline manual for information about the format and
allowable constructs of that file, and the capabilities of the
Readline library in general.

Disponibilité: not Android, not iOS, not WASI.

This module is not supported on mobile platforms or WebAssembly
platforms.

This is an *optional module*. If it is missing from your copy of
CPython, look for documentation from your distributor (that is,
whoever provided Python to you). If you are the distributor, see
Requirements for optional modules.

Disponibilité: Unix.

Note:

  The underlying Readline library API may be implemented by the
  "editline" ("libedit") library instead of GNU readline. On macOS the
  "readline" module detects which library is being used at run
  time.The configuration file for "editline" is different from that of
  GNU readline. If you programmatically load configuration strings you
  can use "backend" to determine which library is being used.If you
  use "editline"/"libedit" readline emulation on macOS, the
  initialization file located in your home directory is named
  ".editrc". For example, the following content in "~/.editrc" will
  turn ON *vi* keybindings and TAB completion:

     python:bind -v
     python:bind ^I rl_complete

  Also note that different libraries may use different history file
  formats. When switching the underlying library, existing history
  files may become unusable.

readline.backend

   The name of the underlying Readline library being used, either
   ""readline"" or ""editline"".

   Ajouté dans la version 3.13.


Fichier d'initialisation
========================

Les fonctions suivantes se rapportent au fichier d'initialisation et à
la configuration utilisateur :

readline.parse_and_bind(string)

   Execute the init line provided in the *string* argument. This calls
   "rl_parse_and_bind()" in the underlying library.

readline.read_init_file([filename])

   Execute a readline initialization file. The default filename is the
   last filename used. This calls "rl_read_init_file()" in the
   underlying library. It raises an auditing event "open" with the
   file name if given, and ""<readline_init_file>"" otherwise,
   regardless of which file the library resolves.

   Modifié dans la version 3.14: The auditing event was added.


Tampon de ligne
===============

Les fonctions suivantes opèrent sur le tampon de ligne :

readline.get_line_buffer()

   Return the current contents of the line buffer ("rl_line_buffer" in
   the underlying library).

readline.insert_text(string)

   Insert text into the line buffer at the cursor position.  This
   calls "rl_insert_text()" in the underlying library, but ignores the
   return value.

readline.redisplay()

   Change what's displayed on the screen to reflect the current
   contents of the line buffer.  This calls "rl_redisplay()" in the
   underlying library.


Fichier d'historique
====================

les fonctions suivantes opèrent sur un fichier d'historique :

readline.read_history_file([filename])

   Load a readline history file, and append it to the history list.
   The default filename is "~/.history".  This calls "read_history()"
   in the underlying library and raises an auditing event "open" with
   the file name if given and ""~/.history"" otherwise.

   Modifié dans la version 3.14: The auditing event was added.

readline.write_history_file([filename])

   Save the history list to a readline history file, overwriting any
   existing file.  The default filename is "~/.history".  This calls
   "write_history()" in the underlying library and raises an auditing
   event "open" with the file name if given and ""~/.history""
   otherwise.

   Modifié dans la version 3.14: The auditing event was added.

readline.append_history_file(nelements[, filename])

   Append the last *nelements* items of history to a file.  The
   default filename is "~/.history".  The file must already exist.
   This calls "append_history()" in the underlying library.  This
   function only exists if Python was compiled for a version of the
   library that supports it. It raises an auditing event "open" with
   the file name if given and ""~/.history"" otherwise.

   Ajouté dans la version 3.5.

   Modifié dans la version 3.14: The auditing event was added.

readline.get_history_length()
readline.set_history_length(length)

   Set or return the desired number of lines to save in the history
   file. The "write_history_file()" function uses this value to
   truncate the history file, by calling "history_truncate_file()" in
   the underlying library.  Negative values imply unlimited history
   file size.


Liste d'historique
==================

Les fonctions suivantes opèrent sur une liste d'historique globale :

readline.clear_history()

   Clear the current history.  This calls "clear_history()" in the
   underlying library.  The Python function only exists if Python was
   compiled for a version of the library that supports it.

readline.get_current_history_length()

   Renvoie le nombre d'objets actuellement dans l'historique. (C'est
   différent de "get_history_length()", qui renvoie le nombre maximum
   de lignes qui vont être écrites dans un fichier d'historique.)

readline.get_history_item(index)

   Return the current contents of history item at *index*.  The item
   index is one-based.  This calls "history_get()" in the underlying
   library.

readline.remove_history_item(pos)

   Remove history item specified by its position from the history. The
   position is zero-based.  This calls "remove_history()" in the
   underlying library.

readline.replace_history_item(pos, line)

   Replace history item specified by its position with *line*. The
   position is zero-based.  This calls "replace_history_entry()" in
   the underlying library.

readline.add_history(line)

   Append *line* to the history buffer, as if it was the last line
   typed. This calls "add_history()" in the underlying library.

readline.set_auto_history(enabled)

   Enable or disable automatic calls to "add_history()" when reading
   input via readline.  The *enabled* argument should be a Boolean
   value that when true, enables auto history, and that when false,
   disables auto history.

   Ajouté dans la version 3.6.

   **Particularité de l'implémentation CPython :** Auto history is
   enabled by default, and changes to this do not persist across
   multiple sessions.


Fonctions de rappel au démarrage
================================

readline.set_startup_hook([function])

   Set or remove the function invoked by the "rl_startup_hook"
   callback of the underlying library.  If *function* is specified, it
   will be used as the new hook function; if omitted or "None", any
   function already installed is removed.  The hook is called with no
   arguments just before readline prints the first prompt.

readline.set_pre_input_hook([function])

   Set or remove the function invoked by the "rl_pre_input_hook"
   callback of the underlying library.  If *function* is specified, it
   will be used as the new hook function; if omitted or "None", any
   function already installed is removed.  The hook is called with no
   arguments after the first prompt has been printed and just before
   readline starts reading input characters.  This function only
   exists if Python was compiled for a version of the library that
   supports it.


Complétion
==========

The following functions relate to implementing a custom word
completion function.  This is typically operated by the Tab key, and
can suggest and automatically complete a word being typed.  By
default, Readline is set up to be used by "rlcompleter" to complete
Python identifiers for the interactive interpreter.  If the "readline"
module is to be used with a custom completer, a different set of word
delimiters should be set.

readline.set_completer([function])

   Définit ou supprime la fonction de complétion. Si *function* est
   spécifié, il sera utilisé en tant que nouvelle fonction de
   complétion; si omis ou "None", toute fonction de complétion déjà
   installé est supprimé. La fonction de complétion est appelée telle
   que "function(text, state)", pour *state* valant "0", "1", "2",
   ..., jusqu'à ce qu'elle renvoie une valeur qui n'est pas une chaîne
   de caractères. Elle doit renvoyer les prochaines complétions
   possibles commençant par *text*.

   The installed completer function is invoked by the *entry_func*
   callback passed to "rl_completion_matches()" in the underlying
   library. The *text* string comes from the first parameter to the
   "rl_attempted_completion_function" callback of the underlying
   library.

readline.get_completer()

   Récupère la fonction de complétion, ou "None" si aucune fonction de
   complétion n'a été définie.

readline.get_completion_type()

   Get the type of completion being attempted.  This returns the
   "rl_completion_type" variable in the underlying library as an
   integer.

readline.get_begidx()
readline.get_endidx()

   Get the beginning or ending index of the completion scope. These
   indexes are the *start* and *end* arguments passed to the
   "rl_attempted_completion_function" callback of the underlying
   library.  The values may be different in the same input editing
   scenario based on the underlying C readline implementation. Ex:
   libedit is known to behave differently than libreadline.

readline.set_completer_delims(string)
readline.get_completer_delims()

   Set or get the word delimiters for completion.  These determine the
   start of the word to be considered for completion (the completion
   scope). These functions access the
   "rl_completer_word_break_characters" variable in the underlying
   library.

readline.set_completion_display_matches_hook([function])

   Set or remove the completion display function.  If *function* is
   specified, it will be used as the new completion display function;
   if omitted or "None", any completion display function already
   installed is removed.  This sets or clears the
   "rl_completion_display_matches_hook" callback in the underlying
   library.  The completion display function is called as
   "function(substitution, [matches], longest_match_length)" once each
   time matches need to be displayed.


Exemple
=======

The following example demonstrates how to use the "readline" module's
history reading and writing functions to automatically load and save a
history file named ".python_history" from the user's home directory.
The code below would normally be executed automatically during
interactive sessions from the user's "PYTHONSTARTUP" file.

   import atexit
   import os
   import readline

   histfile = os.path.join(os.path.expanduser("~"), ".python_history")
   try:
       readline.read_history_file(histfile)
       # default history len is -1 (infinite), which may grow unruly
       readline.set_history_length(1000)
   except FileNotFoundError:
       pass

   atexit.register(readline.write_history_file, histfile)

Ce code est en réalité automatiquement exécuté lorsque Python tourne
en mode interactif (voir Readline configuration).

L'exemple suivant atteint le même objectif mais gère des sessions
interactives concurrentes, en ajoutant seulement le nouvel historique.

   import atexit
   import os
   import readline
   histfile = os.path.join(os.path.expanduser("~"), ".python_history")

   try:
       readline.read_history_file(histfile)
       h_len = readline.get_current_history_length()
   except FileNotFoundError:
       open(histfile, 'wb').close()
       h_len = 0

   def save(prev_h_len, histfile):
       new_h_len = readline.get_current_history_length()
       readline.set_history_length(1000)
       readline.append_history_file(new_h_len - prev_h_len, histfile)
   atexit.register(save, h_len, histfile)

L'exemple suivant étend la classe "code.InteractiveConsole" pour gérer
la sauvegarde/restauration de l'historique.

   import atexit
   import code
   import os
   import readline

   class HistoryConsole(code.InteractiveConsole):
       def __init__(self, locals=None, filename="<console>",
                    histfile=os.path.expanduser("~/.console-history")):
           code.InteractiveConsole.__init__(self, locals, filename)
           self.init_history(histfile)

       def init_history(self, histfile):
           readline.parse_and_bind("tab: complete")
           if hasattr(readline, "read_history_file"):
               try:
                   readline.read_history_file(histfile)
               except FileNotFoundError:
                   pass
               atexit.register(self.save_history, histfile)

       def save_history(self, histfile):
           readline.set_history_length(1000)
           readline.write_history_file(histfile)

Note:

  The new *REPL* introduced in version 3.13 doesn't support readline.
  However, readline can still be used by setting the
  "PYTHON_BASIC_REPL" environment variable.
