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Issue #5845: Enable tab-completion in the interactive interpreter by default, thanks to a new sys.__interactivehook__.
(original patch by Éric Araujo)
This commit is contained in:
Antoine Pitrou
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9 changed files with 143 additions and 165 deletions
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@ -7,140 +7,27 @@ Interactive Input Editing and History Substitution
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Some versions of the Python interpreter support editing of the current input
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line and history substitution, similar to facilities found in the Korn shell and
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the GNU Bash shell. This is implemented using the `GNU Readline`_ library,
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which supports Emacs-style and vi-style editing. This library has its own
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documentation which I won't duplicate here; however, the basics are easily
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explained. The interactive editing and history described here are optionally
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available in the Unix and Cygwin versions of the interpreter.
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This chapter does *not* document the editing facilities of Mark Hammond's
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PythonWin package or the Tk-based environment, IDLE, distributed with Python.
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The command line history recall which operates within DOS boxes on NT and some
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other DOS and Windows flavors is yet another beast.
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.. _tut-lineediting:
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Line Editing
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============
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If supported, input line editing is active whenever the interpreter prints a
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primary or secondary prompt. The current line can be edited using the
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conventional Emacs control characters. The most important of these are:
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:kbd:`C-A` (Control-A) moves the cursor to the beginning of the line, :kbd:`C-E`
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to the end, :kbd:`C-B` moves it one position to the left, :kbd:`C-F` to the
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right. Backspace erases the character to the left of the cursor, :kbd:`C-D` the
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character to its right. :kbd:`C-K` kills (erases) the rest of the line to the
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right of the cursor, :kbd:`C-Y` yanks back the last killed string.
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:kbd:`C-underscore` undoes the last change you made; it can be repeated for
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cumulative effect.
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.. _tut-history:
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History Substitution
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====================
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History substitution works as follows. All non-empty input lines issued are
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saved in a history buffer, and when a new prompt is given you are positioned on
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a new line at the bottom of this buffer. :kbd:`C-P` moves one line up (back) in
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the history buffer, :kbd:`C-N` moves one down. Any line in the history buffer
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can be edited; an asterisk appears in front of the prompt to mark a line as
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modified. Pressing the :kbd:`Return` key passes the current line to the
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interpreter. :kbd:`C-R` starts an incremental reverse search; :kbd:`C-S` starts
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a forward search.
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which supports various styles of editing. This library has its own
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documentation which we won't duplicate here.
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.. _tut-keybindings:
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Key Bindings
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============
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Tab Completion and History Editing
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==================================
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The key bindings and some other parameters of the Readline library can be
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customized by placing commands in an initialization file called
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:file:`~/.inputrc`. Key bindings have the form ::
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key-name: function-name
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or ::
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"string": function-name
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and options can be set with ::
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set option-name value
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For example::
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# I prefer vi-style editing:
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set editing-mode vi
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# Edit using a single line:
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set horizontal-scroll-mode On
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# Rebind some keys:
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Meta-h: backward-kill-word
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"\C-u": universal-argument
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"\C-x\C-r": re-read-init-file
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Note that the default binding for :kbd:`Tab` in Python is to insert a :kbd:`Tab`
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character instead of Readline's default filename completion function. If you
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insist, you can override this by putting ::
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Tab: complete
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in your :file:`~/.inputrc`. (Of course, this makes it harder to type indented
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continuation lines if you're accustomed to using :kbd:`Tab` for that purpose.)
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.. index::
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module: rlcompleter
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module: readline
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Automatic completion of variable and module names is optionally available. To
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enable it in the interpreter's interactive mode, add the following to your
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startup file: [#]_ ::
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import rlcompleter, readline
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readline.parse_and_bind('tab: complete')
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This binds the :kbd:`Tab` key to the completion function, so hitting the
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:kbd:`Tab` key twice suggests completions; it looks at Python statement names,
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the current local variables, and the available module names. For dotted
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expressions such as ``string.a``, it will evaluate the expression up to the
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final ``'.'`` and then suggest completions from the attributes of the resulting
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object. Note that this may execute application-defined code if an object with a
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:meth:`__getattr__` method is part of the expression.
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A more capable startup file might look like this example. Note that this
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deletes the names it creates once they are no longer needed; this is done since
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the startup file is executed in the same namespace as the interactive commands,
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and removing the names avoids creating side effects in the interactive
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environment. You may find it convenient to keep some of the imported modules,
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such as :mod:`os`, which turn out to be needed in most sessions with the
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interpreter. ::
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# Add auto-completion and a stored history file of commands to your Python
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# interactive interpreter. Requires Python 2.0+, readline. Autocomplete is
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# bound to the Esc key by default (you can change it - see readline docs).
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#
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# Store the file in ~/.pystartup, and set an environment variable to point
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# to it: "export PYTHONSTARTUP=~/.pystartup" in bash.
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import atexit
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import os
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import readline
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import rlcompleter
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historyPath = os.path.expanduser("~/.pyhistory")
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def save_history(historyPath=historyPath):
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import readline
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readline.write_history_file(historyPath)
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if os.path.exists(historyPath):
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readline.read_history_file(historyPath)
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atexit.register(save_history)
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del os, atexit, readline, rlcompleter, save_history, historyPath
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Completion of variable and module names is
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:ref:`automatically enabled <rlcompleter-config>` at interpreter startup so
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that the :kbd:`Tab` key invokes the completion function; it looks at
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Python statement names, the current local variables, and the available
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module names. For dotted expressions such as ``string.a``, it will evaluate
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the expression up to the final ``'.'`` and then suggest completions from
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the attributes of the resulting object. Note that this may execute
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application-defined code if an object with a :meth:`__getattr__` method
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is part of the expression. The default configuration also saves your
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history into a file named :file:`.python_history` in your user directory.
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The history will be available again during the next interactive interpreter
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session.
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.. _tut-commentary:
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@ -162,14 +49,6 @@ into other applications. Another similar enhanced interactive environment is
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bpython_.
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.. rubric:: Footnotes
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.. [#] Python will execute the contents of a file identified by the
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:envvar:`PYTHONSTARTUP` environment variable when you start an interactive
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interpreter. To customize Python even for non-interactive mode, see
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:ref:`tut-customize`.
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.. _GNU Readline: http://tiswww.case.edu/php/chet/readline/rltop.html
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.. _IPython: http://ipython.scipy.org/
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.. _bpython: http://www.bpython-interpreter.org/
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