|
|
# encoding: utf-8
|
|
|
|
|
|
"""Manager for replacing sys.displayhook()."""
|
|
|
|
|
|
__docformat__ = "restructuredtext en"
|
|
|
|
|
|
#-------------------------------------------------------------------------------
|
|
|
# Copyright (C) 2008 The IPython Development Team
|
|
|
#
|
|
|
# Distributed under the terms of the BSD License. The full license is in
|
|
|
# the file COPYING, distributed as part of this software.
|
|
|
#-------------------------------------------------------------------------------
|
|
|
|
|
|
#-------------------------------------------------------------------------------
|
|
|
# Imports
|
|
|
#-------------------------------------------------------------------------------
|
|
|
|
|
|
# Standard library imports.
|
|
|
import sys
|
|
|
|
|
|
|
|
|
|
|
|
class DisplayTrap(object):
|
|
|
""" Object to trap and format objects passing through sys.displayhook().
|
|
|
|
|
|
This trap maintains two lists of callables: formatters and callbacks. The
|
|
|
formatters take the *last* object that has gone through since the trap was
|
|
|
set and returns a string representation. Callbacks are executed on *every*
|
|
|
object that passes through the displayhook and does not return anything.
|
|
|
"""
|
|
|
|
|
|
def __init__(self, formatters=None, callbacks=None):
|
|
|
# A list of formatters to apply. Each should be an instance conforming
|
|
|
# to the IDisplayFormatter interface.
|
|
|
if formatters is None:
|
|
|
formatters = []
|
|
|
self.formatters = formatters
|
|
|
|
|
|
# A list of callables, each of which should be executed *every* time an
|
|
|
# object passes through sys.displayhook().
|
|
|
if callbacks is None:
|
|
|
callbacks = []
|
|
|
self.callbacks = callbacks
|
|
|
|
|
|
# The last object to pass through the displayhook.
|
|
|
self.obj = None
|
|
|
|
|
|
# The previous hook before we replace it.
|
|
|
self.old_hook = None
|
|
|
|
|
|
def hook(self, obj):
|
|
|
""" This method actually implements the hook.
|
|
|
"""
|
|
|
|
|
|
# Run through the list of callbacks and trigger all of them.
|
|
|
for callback in self.callbacks:
|
|
|
callback(obj)
|
|
|
|
|
|
# Store the object for formatting.
|
|
|
self.obj = obj
|
|
|
|
|
|
def set(self):
|
|
|
""" Set the hook.
|
|
|
"""
|
|
|
|
|
|
if sys.displayhook is not self.hook:
|
|
|
self.old_hook = sys.displayhook
|
|
|
sys.displayhook = self.hook
|
|
|
|
|
|
def unset(self):
|
|
|
""" Unset the hook.
|
|
|
"""
|
|
|
|
|
|
sys.displayhook = self.old_hook
|
|
|
|
|
|
def clear(self):
|
|
|
""" Reset the stored object.
|
|
|
"""
|
|
|
|
|
|
self.obj = None
|
|
|
|
|
|
def add_to_message(self, message):
|
|
|
""" Add the formatted display of the objects to the message dictionary
|
|
|
being returned from the interpreter to its listeners.
|
|
|
"""
|
|
|
|
|
|
# If there was no displayed object (or simply None), then don't add
|
|
|
# anything.
|
|
|
if self.obj is None:
|
|
|
return
|
|
|
|
|
|
# Go through the list of formatters and let them add their formatting.
|
|
|
display = {}
|
|
|
for formatter in self.formatters:
|
|
|
representation = formatter(self.obj)
|
|
|
if representation is not None:
|
|
|
display[formatter.identifier] = representation
|
|
|
|
|
|
message['display'] = display
|
|
|
|
|
|
|
