docs/source/whatsnew/version6.rst

============
 6.x Series
============


.. _whatsnew631:

IPython 6.3.1
=============

This is a bugfix release to switch the default completions back to IPython's
own completion machinery. We discovered some problems with the completions
from Jedi, including completing column names on pandas data frames.

You can switch the completions source with the config option
:configtrait:`Completer.use_jedi`.

.. _whatsnew630:

IPython 6.3
===========

IPython 6.3 contains all the bug fixes and features in
:ref:`IPython 5.6 <whatsnew560>`. In addition:

* A new display class :class:`IPython.display.Code` can be used to display
  syntax highlighted code in a notebook (:ghpull:`10978`).
* The :cellmagic:`html` magic now takes a ``--isolated`` option to put the
  content in an iframe (:ghpull:`10962`).
* The code to find completions using the Jedi library has had various
  adjustments. This is still a work in progress, but we hope this version has
  fewer annoyances (:ghpull:`10956`, :ghpull:`10969`, :ghpull:`10999`,
  :ghpull:`11035`, :ghpull:`11063`, :ghpull:`11065`).
* The *post* event callbacks are now always called, even when the execution failed
  (for example because of a ``SyntaxError``).
* The execution info and result objects are now made available in the
  corresponding *pre* or *post* ``*_run_cell`` :doc:`event callbacks </config/callbacks>`
  in a backward compatible manner (:ghissue:`10774` and :ghpull:`10795`).
* Performance with very long code cells (hundreds of lines) is greatly improved
  (:ghpull:`10898`). Further improvements are planned for IPython 7.

You can see all `pull requests for the 6.3 milestone
<https://github.com/ipython/ipython/pulls?utf8=%E2%9C%93&q=is%3Apr+milestone%3A6.3+is%3Aclosed>`__.

.. _whatsnew620:

IPython 6.2
===========

IPython 6.2 contains all the bugs fixes and features :ref:`available in IPython 5.5 <whatsnew550>`,
like built in progress bar support, and system-wide configuration

The following features are specific to IPython 6.2:

Function signature in completions
---------------------------------

Terminal IPython will now show the signature of the function while completing.
Only the currently highlighted function will show its signature on the line
below the completer by default. This functionality is recent, so it might be
limited; we welcome bug reports and requests for enhancements. :ghpull:`10507`

Assignments return values
-------------------------

IPython can now trigger the display hook on the last assignment of cells.
Up until 6.2 the following code wouldn't show the value of the assigned
variable::

    In[1]: xyz = "something"
    # nothing shown

You would have to actually make it the last statement::

    In [2]: xyz = "something else"
    ...   : xyz
    Out[2]: "something else"

With the option ``InteractiveShell.ast_node_interactivity='last_expr_or_assign'``
you can now do::

    In [2]: xyz = "something else"
    Out[2]: "something else"

This option can be toggled at runtime with the ``%config`` magic, and will
trigger on assignment ``a = 1``, augmented assignment ``+=``, ``-=``, ``|=`` ...
as well as type annotated assignments: ``a:int = 2``.

See :ghpull:`10598`

Recursive Call of ipdb
----------------------

Advanced users of the debugger can now correctly recursively enter ipdb. This is
thanks to ``@segevfiner`` on :ghpull:`10721`.

.. _whatsnew610:

IPython 6.1
===========

- Quotes in a filename are always escaped during tab-completion on non-Windows.
  :ghpull:`10069`

- Variables now shadow magics in autocompletion. See :ghissue:`4877` and :ghpull:`10542`.

- Added the ability to add parameters to alias_magic. For example::

    In [2]: %alias_magic hist history --params "-l 2" --line
    Created `%hist` as an alias for `%history -l 2`.

    In [3]: hist
    %alias_magic hist history --params "-l 30" --line
    %alias_magic hist history --params "-l 2" --line

  Previously it was only possible to have an alias attached to a single function,
  and you would have to pass in the given parameters every time::

    In [4]: %alias_magic hist history --line
    Created `%hist` as an alias for `%history`.

    In [5]: hist -l 2
    hist
    %alias_magic hist history --line

- To suppress log state messages, you can now either use ``%logstart -q``, pass
  ``--LoggingMagics.quiet=True`` on the command line, or set
  ``c.LoggingMagics.quiet=True`` in your configuration file.

- An additional flag ``--TerminalInteractiveShell.term_title_format`` is
  introduced to allow the user to control the format of the terminal title.  It
  is specified as a python format string, and currently the only variable it
  will format is ``{cwd}``.

- ``??``/``%pinfo2`` will now show object docstrings if the source can't be retrieved. :ghpull:`10532`
- ``IPython.display`` has gained a ``%markdown`` cell magic. :ghpull:`10563`
- ``%config`` options can now be tab completed. :ghpull:`10555`
- ``%config`` with no arguments are now unique and sorted. :ghpull:`10548`
- Completion on keyword arguments does not duplicate ``=`` sign if already present. :ghpull:`10547`
- ``%run -m <module>`` now ``<module>`` passes extra arguments to ``<module>``. :ghpull:`10546`
- completer now understand "snake case auto complete": if ``foo_bar_kittens`` is
  a valid completion, I can type ``f_b<tab>`` will complete to it. :ghpull:`10537`
- tracebacks are better standardized and will compress `/path/to/home` to `~`. :ghpull:`10515`

The following changes were also added to IPython 5.4, see :ref:`what's new in IPython 5.4 <whatsnew540>`
for more detail description:

- ``TerminalInteractiveShell`` is configurable and can be configured to
  (re)-use the readline interface.

- objects can now define a ``_repr_mimebundle_``

- Execution heuristics improve for single line statements
- ``display()`` can now return a display id to update display areas.


.. _whatsnew600:

IPython 6.0
===========

Released April 19th, 2017

IPython 6 features a major improvement in the completion machinery which is now
capable of completing non-executed code. It is also the first version of IPython
to stop compatibility with Python 2, which is still supported on the bugfix only
5.x branch. Read below for a non-exhaustive list of new features.

Make sure you have pip > 9.0 before upgrading.
You should be able to update by using:

.. code::

    pip install ipython --upgrade


.. note::

    If your pip version is greater than or equal to pip 9.0.1 you will automatically get
    the most recent version of IPython compatible with your system: on Python 2 you 
    will get the latest IPython 5.x bugfix, while in Python 3
    you will get the latest 6.x stable version.

New completion API and Interface
--------------------------------

The completer Completion API has seen an overhaul, and the new completer has
plenty of improvements both from the end users of terminal IPython and for
consumers of the API.

This new API is capable of pulling completions from :any:`jedi`, thus allowing
type inference on non-executed code. If :any:`jedi` is installed, completions like
the following are now possible without code evaluation:

    >>> data = ['Number of users', 123_456]
    ... data[0].<tab>

That is to say, IPython is now capable of inferring that `data[0]` is a string,
and will suggest completions like `.capitalize`. The completion power of IPython
will increase with new Jedi releases, and a number of bug-fixes and more completions
are already available on the development version of :any:`jedi` if you are curious.

With the help of prompt toolkit, types of completions can be shown in the
completer interface:

.. image:: ../_images/jedi_type_inference_60.png
    :alt: Jedi showing ability to do type inference
    :align: center
    :width: 400px
    :target: ../_images/jedi_type_inference_60.png

The appearance of the completer is controlled by the
``c.TerminalInteractiveShell.display_completions`` option that will show the
type differently depending on the value among ``'column'``, ``'multicolumn'``
and ``'readlinelike'``

The use of Jedi also fulfills a number of requests and fixes a number of bugs
like case-insensitive completion and completion after division operator: See
:ghpull:`10182`.

Extra patches and updates will be needed to the :mod:`ipykernel` package for
this feature to be available to other clients like Jupyter Notebook, Lab,
Nteract, Hydrogen...

The use of Jedi should be barely noticeable on recent machines, but 
can be slower on older ones.  To tweak the performance, the amount
of time given to Jedi to compute type inference can be adjusted with
``c.IPCompleter.jedi_compute_type_timeout``. The objects whose type were not
inferred will be shown as ``<unknown>``. Jedi can also be completely deactivated
by using the ``c.Completer.use_jedi=False`` option.


The old ``Completer.complete()`` API is waiting deprecation and should be
replaced replaced by ``Completer.completions()`` in the near future. Feedback on
the current state of the API and suggestions are welcome.

Python 3 only codebase
----------------------

One of the large challenges in IPython 6.0 has been the adoption of a pure
Python 3 codebase, which has led to upstream patches in pip,
pypi and warehouse to make sure Python 2 systems still upgrade to the latest
compatible Python version.

We remind our Python 2 users that IPython 5 is still compatible with Python 2.7,
still maintained and will get regular releases. Using pip 9+, upgrading IPython will
automatically upgrade to the latest version compatible with your system.

.. warning::

  If you are on a system using an older version of pip on Python 2, pip may
  still install IPython 6.0 on your system, and IPython will refuse to start.
  You can fix this by upgrading pip, and reinstalling ipython, or forcing pip to
  install an earlier version: ``pip install 'ipython<6'``

The ability to use only Python 3 on the code base of IPython brings a number
of advantages. Most of the newly written code make use of `optional function type
annotation <https://www.python.org/dev/peps/pep-0484/>`_ leading to clearer code
and better documentation.

The total size of the repository has also decreased by about 1500 lines (for the 
first time excluding the big split for 4.0). The decrease is potentially
a bit more for the sour as some documents like this one are append only and
are about 300 lines long.

The removal of the Python2/Python3 shim layer has made the code quite a lot clearer and
more idiomatic in a number of locations, and much friendlier to work with and
understand. We hope to further embrace Python 3 capabilities in the next release
cycle and introduce more of the Python 3 only idioms (yield from, kwarg only,
general unpacking) in the IPython code base, and see if we can take advantage
of these to improve user experience with better error messages and
hints.


Configurable TerminalInteractiveShell, readline interface
---------------------------------------------------------

IPython gained a new ``c.TerminalIPythonApp.interactive_shell_class`` option
that allows customizing the class used to start the terminal frontend. This
should allow a user to use custom interfaces, like reviving the former readline
interface which is now a separate package not actively maintained by the core
team. See the project to bring back the readline interface: `rlipython
<https://github.com/ipython/rlipython>`_.

This change will be backported to the IPython 5.x series.

Misc improvements
-----------------


- The :cellmagic:`capture` magic can now capture the result of a cell (from
  an expression on the last line), as well as printed and displayed output.
  :ghpull:`9851`.

- Pressing Ctrl-Z in the terminal debugger now suspends IPython, as it already
  does in the main terminal prompt.

- Autoreload can now reload ``Enum``. See :ghissue:`10232` and :ghpull:`10316`

- IPython.display has gained a :any:`GeoJSON <IPython.display.GeoJSON>` object.
  :ghpull:`10288` and :ghpull:`10253`

Functions Deprecated in 6.x Development cycle
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- Loading extensions from ``ipython_extension_dir`` prints a warning that this
  location is pending deprecation. This should only affect users still having
  extensions installed with ``%install_ext`` which has been deprecated since
  IPython 4.0, and removed in 5.0. Extensions still present in
  ``ipython_extension_dir`` may shadow more recently installed versions using
  pip. It is thus recommended to clean ``ipython_extension_dir`` of any
  extension now available as a package.


- ``IPython.utils.warn`` was deprecated in IPython 4.0, and has now been removed.
  instead of ``IPython.utils.warn`` inbuilt :any:`warnings` module is used.


- The function `IPython.core.oinspect.py:call_tip` is unused, was marked as
  deprecated (raising a `DeprecationWarning`) and marked for later removal.
  :ghpull:`10104`

Backward incompatible changes
------------------------------

Functions Removed in 6.x Development cycle
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The following functions have been removed in the
development cycle marked for Milestone 6.0.

- ``IPython/utils/process.py`` - ``is_cmd_found``
- ``IPython/utils/process.py`` - ``pycmd2argv``

- The `--deep-reload` flag and the corresponding options to inject `dreload` or
  `reload` into the interactive namespace have been removed. You have to
  explicitly import `reload` from `IPython.lib.deepreload` to use it.

- The :magic:`profile` used to print the current IPython profile, and which
  was deprecated in IPython 2.0 does now raise a `DeprecationWarning` error when
  used. It is often confused with the :magic:`prun` and the deprecation removal
  should free up the ``profile`` name in future versions.