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Implement a context manager as a property locking mechanism in Widget.

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This commit is contained in:
Jonathan Frederic 2014-01-08 12:59:48 +00:00
parent 70c6a295d0
commit be268dcf98
1 changed files with 16 additions and 8 deletions
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24
IPython/html/widgets/widget.py
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@ -14,6 +14,7 @@ in the IPython notebook frontend.
#-----------------------------------------------------------------------------
from copy import copy
from glob import glob
from contextlib import contextmanager
import uuid
import sys
import os
@ -30,6 +31,17 @@ from IPython.utils.py3compat import string_types
#-----------------------------------------------------------------------------
# Classes
#-----------------------------------------------------------------------------
@contextmanager
def PropertyLock(instance, key, value):
instance._property_lock = (key, value)
yield
del instance._property_lock
def should_send_property(instance, key, value):
return not hasattr(instance, _property_lock) or \
key != instance._property_lock[0] or \
value != instance._property_lock[1]
class Widget(LoggingConfigurable):
@ -58,8 +70,6 @@ class Widget(LoggingConfigurable):
to use to represent the widget.""")
# Private/protected declarations
# todo: change this to a context manager
_property_lock = (None, None) # Last updated (key, value) from the front-end. Prevents echo.
_comm = Instance('IPython.kernel.comm.Comm')
def __init__(self, **kwargs):
@ -114,11 +124,9 @@ class Widget(LoggingConfigurable):
"""Called when a state is recieved from the frontend."""
for name in self.keys:
if name in sync_data:
try:
self._property_lock = (name, sync_data[name])
setattr(self, name, sync_data[name])
finally:
self._property_lock = (None, None)
value = sync_data[name]
with PropertyLock(self, name, value):
setattr(self, name, value)
def _handle_custom_msg(self, content):
@ -145,7 +153,7 @@ class Widget(LoggingConfigurable):
def _handle_property_changed(self, name, old, new):
"""Called when a property has been changed."""
# Make sure this isn't information that the front-end just sent us.
if self._property_lock[0] != name and self._property_lock[1] != new:
if should_send_property(self, name, new):
# Send new state to frontend
self.send_state(key=name)