core.display_trap

Module: core.display_trap

Inheritance diagram for IPython.core.display_trap:

A context manager for handling sys.displayhook.

Authors:

• Robert Kern
• Brian Granger

DisplayTrap

class IPython.core.display_trap.DisplayTrap(hook=None)

Bases: IPython.config.configurable.Configurable

Object to manage sys.displayhook.

This came from IPython.core.kernel.display_hook, but is simplified (no callbacks or formatters) until more of the core is refactored.

__init__(hook=None)

classmethod class_config_section()

Get the config class config section

classmethod class_get_help(inst=None)

Get the help string for this class in ReST format.

If inst is given, it’s current trait values will be used in place of class defaults.

classmethod class_get_trait_help(trait, inst=None)

Get the help string for a single trait.

If inst is given, it’s current trait values will be used in place of the class default.

classmethod class_print_help(inst=None)

Get the help string for a single trait and print it.

classmethod class_trait_names(**metadata)

Get a list of all the names of this classes traits.

This method is just like the trait_names() method, but is unbound.

classmethod class_traits(**metadata)

Get a list of all the traits of this class.

This method is just like the traits() method, but is unbound.

The TraitTypes returned don’t know anything about the values that the various HasTrait’s instances are holding.

This follows the same algorithm as traits does and does not allow for any simple way of specifying merely that a metadata name exists, but has any value. This is because get_metadata returns None if a metadata key doesn’t exist.

config

A trait whose value must be an instance of a specified class.

The value can also be an instance of a subclass of the specified class.

hook

on_trait_change(handler, name=None, remove=False)

Setup a handler to be called when a trait changes.

This is used to setup dynamic notifications of trait changes.

Static handlers can be created by creating methods on a HasTraits subclass with the naming convention ‘_[traitname]_changed’. Thus, to create static handler for the trait ‘a’, create the method _a_changed(self, name, old, new) (fewer arguments can be used, see below).

Parameters :

handler : callable

A callable that is called when a trait changes. Its signature can be handler(), handler(name), handler(name, new) or handler(name, old, new).

name : list, str, None

If None, the handler will apply to all traits. If a list of str, handler will apply to all names in the list. If a str, the handler will apply just to that name.

remove : bool

If False (the default), then install the handler. If True then unintall it.

set()

Set the hook.

trait_metadata(traitname, key)

Get metadata values for trait by key.

trait_names(**metadata)

Get a list of all the names of this classes traits.

traits(**metadata)

Get a list of all the traits of this class.

The TraitTypes returned don’t know anything about the values that the various HasTrait’s instances are holding.

This follows the same algorithm as traits does and does not allow for any simple way of specifying merely that a metadata name exists, but has any value. This is because get_metadata returns None if a metadata key doesn’t exist.

unset()

Unset the hook.

update_config(config)

Fire the traits events when the config is updated.