integrating.rst
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r8083 | .. _integrating: | ||
===================================== | ||||
Integrating your objects with IPython | ||||
===================================== | ||||
Tab completion | ||||
============== | ||||
To change the attributes displayed by tab-completing your object, define a | ||||
``__dir__(self)`` method for it. For more details, see the documentation of the | ||||
built-in `dir() function <http://docs.python.org/library/functions.html#dir>`_. | ||||
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r22147 | You can also customise key completions for your objects, e.g. pressing tab after | ||
``obj["a``. To do so, define a method ``_ipython_key_completions_()``, which | ||||
returns a list of objects which are possible keys in a subscript expression | ||||
``obj[key]``. | ||||
.. versionadded:: 5.0 | ||||
Custom key completions | ||||
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r24041 | .. _integrating_rich_display: | ||
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r8083 | Rich display | ||
============ | ||||
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r26580 | Custom methods | ||
---------------------- | ||||
IPython can display richer representations of objects. | ||||
To do this, you can define ``_ipython_display_()``, or any of a number of | ||||
``_repr_*_()`` methods. | ||||
Note that these are surrounded by single, not double underscores. | ||||
.. list-table:: Supported ``_repr_*_`` methods | ||||
:widths: 20 15 15 15 | ||||
:header-rows: 1 | ||||
* - Format | ||||
- REPL | ||||
- Notebook | ||||
- Qt Console | ||||
* - ``_repr_pretty_`` | ||||
- yes | ||||
- yes | ||||
- yes | ||||
* - ``_repr_svg_`` | ||||
- no | ||||
- yes | ||||
- yes | ||||
* - ``_repr_png_`` | ||||
- no | ||||
- yes | ||||
- yes | ||||
* - ``_repr_jpeg_`` | ||||
- no | ||||
- yes | ||||
- yes | ||||
* - ``_repr_html_`` | ||||
- no | ||||
- yes | ||||
- no | ||||
* - ``_repr_javascript_`` | ||||
- no | ||||
- yes | ||||
- no | ||||
* - ``_repr_markdown_`` | ||||
- no | ||||
- yes | ||||
- no | ||||
* - ``_repr_latex_`` | ||||
- no | ||||
- yes | ||||
- no | ||||
* - ``_repr_mimebundle_`` | ||||
- no | ||||
- ? | ||||
- ? | ||||
If the methods don't exist, or return ``None``, the standard ``repr()`` is used. | ||||
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r8083 | |||
For example:: | ||||
class Shout(object): | ||||
def __init__(self, text): | ||||
self.text = text | ||||
def _repr_html_(self): | ||||
return "<h1>" + self.text + "</h1>" | ||||
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r24302 | |||
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r26580 | Special methods | ||
^^^^^^^^^^^^^^^ | ||||
Pretty printing | ||||
""""""""""""""" | ||||
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r26581 | To customize how your object is pretty-printed, add a ``_repr_pretty_`` method | ||
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r26580 | to the class. | ||
The method should accept a pretty printer, and a boolean that indicates whether | ||||
the printer detected a cycle. | ||||
The method should act on the printer to produce your customized pretty output. | ||||
Here is an example:: | ||||
class MyObject(object): | ||||
def _repr_pretty_(self, p, cycle): | ||||
if cycle: | ||||
p.text('MyObject(...)') | ||||
else: | ||||
p.text('MyObject[...]') | ||||
For details on how to use the pretty printer, see :py:mod:`IPython.lib.pretty`. | ||||
More powerful methods | ||||
""""""""""""""""""""" | ||||
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r24036 | |||
.. class:: MyObject | ||||
.. method:: _repr_mimebundle_(include=None, exclude=None) | ||||
Should return a dictionary of multiple formats, keyed by mimetype, or a tuple | ||||
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r26580 | of two dictionaries: *data, metadata* (see :ref:`Metadata`). | ||
If this returns something, other ``_repr_*_`` methods are ignored. | ||||
The method should take keyword arguments ``include`` and ``exclude``, though | ||||
it is not required to respect them. | ||||
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r24036 | |||
.. method:: _ipython_display_() | ||||
Displays the object as a side effect; the return value is ignored. If this | ||||
is defined, all other display methods are ignored. | ||||
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r26580 | This method is ignored in the REPL. | ||
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r24036 | |||
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r24620 | |||
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r26580 | Metadata | ||
^^^^^^^^ | ||||
We often want to provide frontends with guidance on how to display the data. To | ||||
support this, ``_repr_*_()`` methods (except `_repr_pretty_``?) can also return a ``(data, metadata)`` | ||||
tuple where ``metadata`` is a dictionary containing arbitrary key-value pairs for | ||||
the frontend to interpret. An example use case is ``_repr_jpeg_()``, which can | ||||
be set to return a jpeg image and a ``{'height': 400, 'width': 600}`` dictionary | ||||
to inform the frontend how to size the image. | ||||
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r24620 | |||
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r24036 | Formatters for third-party types | ||
-------------------------------- | ||||
The user can also register formatters for types without modifying the class:: | ||||
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r25165 | from bar.baz import Foo | ||
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r24036 | |||
def foo_html(obj): | ||||
return '<marquee>Foo object %s</marquee>' % obj.name | ||||
html_formatter = get_ipython().display_formatter.formatters['text/html'] | ||||
html_formatter.for_type(Foo, foo_html) | ||||
# Or register a type without importing it - this does the same as above: | ||||
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r25165 | html_formatter.for_type_by_name('bar.baz', 'Foo', foo_html) | ||
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r24036 | |||
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r8083 | Custom exception tracebacks | ||
=========================== | ||||
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r22788 | Rarely, you might want to display a custom traceback when reporting an | ||
exception. To do this, define the custom traceback using | ||||
`_render_traceback_(self)` method which returns a list of strings, one string | ||||
for each line of the traceback. For example, the `ipyparallel | ||||
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r26565 | <https://ipyparallel.readthedocs.io/>`__ a parallel computing framework for | ||
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r22788 | IPython, does this to display errors from multiple engines. | ||
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r8083 | |||
Please be conservative in using this feature; by replacing the default traceback | ||||
you may hide important information from the user. | ||||