docs/source/config/details.rst

=======================
Specific config details
=======================

.. _custom_prompts:

Custom Prompts
==============

.. versionchanged:: 5.0

From IPython 5, prompts are produced as a list of Pygments tokens, which are
tuples of (token_type, text). You can customise prompts by writing a method
which generates a list of tokens.

There are four kinds of prompt:

* The **in** prompt is shown before the first line of input
  (default like ``In [1]:``).
* The **continuation** prompt is shown before further lines of input
  (default like ``...:``).
* The **rewrite** prompt is shown to highlight how special syntax has been
  interpreted (default like ``----->``).
* The **out** prompt is shown before the result from evaluating the input
  (default like ``Out[1]:``).

Custom prompts are supplied together as a class. If you want to customise only
some of the prompts, inherit from :class:`IPython.terminal.prompts.Prompts`,
which defines the defaults. The required interface is like this:

.. class:: MyPrompts(shell)

   Prompt style definition. *shell* is a reference to the
   :class:`~.TerminalInteractiveShell` instance.

   .. method:: in_prompt_tokens(cli=None)
               continuation_prompt_tokens(self, cli=None, width=None)
               rewrite_prompt_tokens()
               out_prompt_tokens()

      Return the respective prompts as lists of ``(token_type, text)`` tuples.

      For continuation prompts, *width* is an integer representing the width of
      the prompt area in terminal columns.

      *cli*, where used, is the prompt_toolkit ``CommandLineInterface`` instance.
      This is mainly for compatibility with the API prompt_toolkit expects.

Here is an example Prompt class that will show the current working directory
in the input prompt:

.. code-block:: python

    from IPython.terminal.prompts import Prompts, Token
    import os

    class MyPrompt(Prompts):
         def in_prompt_tokens(self, cli=None):
             return [(Token, os.getcwd()),
                     (Token.Prompt, ' >>>')]

To set the new prompt, assign it to the ``prompts`` attribute of the IPython
shell:

.. code-block:: python

    In [2]: ip = get_ipython()
       ...: ip.prompts = MyPrompt(ip)

    /home/bob >>> # it works

See ``IPython/example/utils/cwd_prompt.py`` for an example of how to write an
extensions to customise prompts.

Inside IPython or in a startup script, you can use a custom prompts class
by setting ``get_ipython().prompts`` to an *instance* of the class.
In configuration, ``TerminalInteractiveShell.prompts_class`` may be set to
either the class object, or a string of its full importable name.

To include invisible terminal control sequences in a prompt, use
``Token.ZeroWidthEscape`` as the token type. Tokens with this type are ignored
when calculating the width.

Colours in the prompt are determined by the token types and the highlighting
style; see below for more details. The tokens used in the default prompts are
``Prompt``, ``PromptNum``, ``OutPrompt`` and ``OutPromptNum``.

.. _termcolour:

Terminal Colors
===============

.. versionchanged:: 5.0

There are two main configuration options controlling colours.

``InteractiveShell.colors`` sets the colour of tracebacks and object info (the
output from e.g. ``zip?``). It may also affect other things if the option below
is set to ``'legacy'``. It has four case-insensitive values:
``'nocolor', 'neutral', 'linux', 'lightbg'``. The default is *neutral*, which
should be legible on either dark or light terminal backgrounds. *linux* is
optimised for dark backgrounds and *lightbg* for light ones.

``TerminalInteractiveShell.highlighting_style`` determines prompt colours and
syntax highlighting. It takes the name (as a string) or class (as a subclass of
``pygments.style.Style``) of a Pygments style, or the special value ``'legacy'``
to pick a style in accordance with ``InteractiveShell.colors``.

You can see the Pygments styles available on your system by running::

    import pygments
    list(pygments.styles.get_all_styles())

Additionally, ``TerminalInteractiveShell.highlighting_style_overrides`` can override
specific styles in the highlighting. It should be a dictionary mapping Pygments
token types to strings defining the style. See `Pygments' documentation
<http://pygments.org/docs/styles/#creating-own-styles>`__ for the language used
to define styles.

Colors in the pager
-------------------

On some systems, the default pager has problems with ANSI colour codes.
To configure your default pager to allow these:

1. Set the environment PAGER variable to ``less``.
2. Set the environment LESS variable to ``-r`` (plus any other options
   you always want to pass to less by default). This tells less to
   properly interpret control sequences, which is how color
   information is given to your terminal.

.. _editors:

Editor configuration
====================

IPython can integrate with text editors in a number of different ways:

* Editors (such as `(X)Emacs`_, vim_ and TextMate_) can
  send code to IPython for execution.

* IPython's ``%edit`` magic command can open an editor of choice to edit
  a code block.

The %edit command (and its alias %ed) will invoke the editor set in your
environment as :envvar:`EDITOR`. If this variable is not set, it will default
to vi under Linux/Unix and to notepad under Windows. You may want to set this
variable properly and to a lightweight editor which doesn't take too long to
start (that is, something other than a new instance of Emacs). This way you
can edit multi-line code quickly and with the power of a real editor right
inside IPython.

You can also control the editor by setting :attr:`TerminalInteractiveShell.editor`
in :file:`ipython_config.py`.

Vim
---

Paul Ivanov's `vim-ipython <https://github.com/ivanov/vim-ipython>`_ provides
powerful IPython integration for vim.

.. _emacs:

(X)Emacs
--------

If you are a dedicated Emacs user, and want to use Emacs when IPython's
``%edit`` magic command is called you should set up the Emacs server so that
new requests are handled by the original process. This means that almost no
time is spent in handling the request (assuming an Emacs process is already
running). For this to work, you need to set your EDITOR environment variable
to 'emacsclient'. The code below, supplied by Francois Pinard, can then be
used in your :file:`.emacs` file to enable the server:

.. code-block:: common-lisp

    (defvar server-buffer-clients)
    (when (and (fboundp 'server-start) (string-equal (getenv "TERM") 'xterm))
      (server-start)
      (defun fp-kill-server-with-buffer-routine ()
        (and server-buffer-clients (server-done)))
      (add-hook 'kill-buffer-hook 'fp-kill-server-with-buffer-routine))

Thanks to the work of Alexander Schmolck and Prabhu Ramachandran,
currently (X)Emacs and IPython get along very well in other ways.

With (X)EMacs >= 24, You can enable IPython in python-mode with:

.. code-block:: common-lisp

    (require 'python)
    (setq python-shell-interpreter "ipython")

.. _`(X)Emacs`: http://www.gnu.org/software/emacs/
.. _TextMate: http://macromates.com/
.. _vim: http://www.vim.org/

.. _custom_keyboard_shortcuts:

Keyboard Shortcuts
==================

.. versionchanged:: 5.0

You can customise keyboard shortcuts for terminal IPython. Put code like this in
a :ref:`startup file <startup_files>`::

    from IPython import get_ipython
    from prompt_toolkit.enums import DEFAULT_BUFFER
    from prompt_toolkit.keys import Keys
    from prompt_toolkit.filters import HasFocus, HasSelection, ViInsertMode, EmacsInsertMode

    ip = get_ipython()
    insert_mode = ViInsertMode() | EmacsInsertMode()

    def insert_unexpected(event):
        buf = event.current_buffer
        buf.insert_text('The Spanish Inquisition')
    # Register the shortcut if IPython is using prompt_toolkit
    if getattr(ip, 'pt_app', None):
        registry = ip.pt_app.key_bindings
        registry.add_binding(Keys.ControlN,
                         filter=(HasFocus(DEFAULT_BUFFER)
                                 & ~HasSelection()
                                 & insert_mode))(insert_unexpected)


Here is a second example that bind the key sequence ``j``, ``k`` to switch to
VI input mode to ``Normal`` when in insert mode::

   from IPython import get_ipython
   from prompt_toolkit.enums import DEFAULT_BUFFER
   from prompt_toolkit.filters import HasFocus, ViInsertMode
   from prompt_toolkit.key_binding.vi_state import InputMode

   ip = get_ipython()

   def switch_to_navigation_mode(event):
      vi_state = event.cli.vi_state
      vi_state.input_mode = InputMode.NAVIGATION

   if getattr(ip, 'pt_app', None):
      registry = ip.pt_app.key_bindings
      registry.add_binding(u'j',u'k',
                           filter=(HasFocus(DEFAULT_BUFFER)
                                    & ViInsertMode()))(switch_to_navigation_mode)

For more information on filters and what you can do with the ``event`` object,
`see the prompt_toolkit docs
<https://python-prompt-toolkit.readthedocs.io/en/latest/pages/asking_for_input.html#adding-custom-key-bindings>`__.


Enter to execute
----------------

In the Terminal IPython shell – which by default uses the ``prompt_toolkit``
interface, the semantic meaning of pressing the :kbd:`Enter` key can be
ambiguous. In some case :kbd:`Enter` should execute code, and in others it
should add a new line. IPython uses heuristics to decide whether to execute or
insert a new line at cursor position. For example, if we detect that the current
code is not valid Python, then the user is likely editing code and the right
behavior is to likely to insert a new line. If the current code is a simple
statement like `ord('*')`, then the right behavior is likely to execute. Though
the exact desired semantics often varies from users to users.

As the exact behavior of :kbd:`Enter` is ambiguous, it has been special cased
to allow users to completely configure the behavior they like. Hence you can
have enter always execute code. If you prefer fancier behavior, you need to get
your hands dirty and read the ``prompt_toolkit`` and IPython documentation
though. See :ghpull:`10500`, set the
``c.TerminalInteractiveShell.handle_return`` option and get inspiration from the
following example that only auto-executes the input if it begins with a bang or
a modulo character (``!`` or ``%``). To use the following code, add it to your
IPython configuration::

    def custom_return(shell):

        """This function is required by the API. It takes a reference to
        the shell, which is the same thing `get_ipython()` evaluates to.
        This function must return a function that handles each keypress
        event. That function, named `handle` here, references `shell`
        by closure."""

        def handle(event):

            """This function is called each time `Enter` is pressed,
            and takes a reference to a Prompt Toolkit event object.
            If the current input starts with a bang or modulo, then
            the input is executed, otherwise a newline is entered,
            followed by any spaces needed to auto-indent."""

            # set up a few handy references to nested items...

            buffer = event.current_buffer
            document = buffer.document
            text = document.text

            if text.startswith('!') or text.startswith('%'): # execute the input...

                buffer.accept_action.validate_and_handle(event.cli, buffer)

            else: # insert a newline with auto-indentation...

                if document.line_count > 1: text = text[:document.cursor_position]
                indent = shell.check_complete(text)[1]
                buffer.insert_text('\n' + indent)
            
                # if you just wanted a plain newline without any indentation, you
                # could use `buffer.insert_text('\n')` instead of the lines above

        return handle

    c.TerminalInteractiveShell.handle_return = custom_return