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.
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]
.
New in version 5.0: Custom key completions
Rich display¶
The notebook and the Qt console can display richer representations of objects.
To use this, you can define any of a number of _repr_*_()
methods. Note that
these are surrounded by single, not double underscores.
Both the notebook and the Qt console can display svg
, png
and jpeg
representations. The notebook can also display html
, javascript
,
and latex
. If the methods don’t exist, or return None
, it falls
back to a standard repr()
.
For example:
class Shout(object):
def __init__(self, text):
self.text = text
def _repr_html_(self):
return "<h1>" + self.text + "</h1>"
Custom exception tracebacks¶
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 a parallel computing framework for
IPython, does this to display errors from multiple engines.
Please be conservative in using this feature; by replacing the default traceback you may hide important information from the user.