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'''
Global registry to register that an Python Object should
be scheduled for garbage collection, when a
QObject is destroyed.
This is used to combine models and views, where
the model should be garbage collected once it has
no views any more. But as long as it has views, it
should be kept alive.
'''
import logging
import six
from ..core.qt import QtCore, valid_variant, variant_to_py
LOGGER = logging.getLogger('camelot.view.register')
[docs]class Register(QtCore.QObject):
"""The register that takes care of the dependencies.
It monitors an object and when the monitored object
is destroyed, its registered object is scheduled for
collection.
"""
def __init__(self):
super(Register, self).__init__()
self._key_name = 'monitor_key'
self._max_monitor_key = 0
self._registed_by_monitor_key = dict()
[docs] def register(self, registered, monitored):
"""
:param registered: the object that will be registered
:param monitored: the object that will be monitored
"""
if valid_variant( monitored.property(self._key_name) ):
key = variant_to_py(monitored.property( self._key_name ))
else:
self._max_monitor_key += 1
key = self._max_monitor_key
monitored.destroyed[QtCore.QObject].connect( self._monitored_object_destroyed )
LOGGER.debug('monitor object with key %s'%key)
self._registed_by_monitor_key[key] = registered
monitored.setProperty( self._key_name, key )
@QtCore.qt_slot(QtCore.QObject)
def _monitored_object_destroyed(self, qobject):
"""slot to indicate a monitored object is destroyed"""
key = variant_to_py( qobject.property( self._key_name ) )
LOGGER.debug('object with key %s is destroyed'%key)
del self._registed_by_monitor_key[key]
_global_register_ = None
[docs]def register(registered, monitored):
"""Global function to register an object and start monitoring
the dependent object
This function takes care of creating the global register as well.
"""
global _global_register_
if _global_register_ == None:
_global_register_ = Register()
_global_register_.register(registered, monitored)
[docs]def dump_register( logger ):
"""Method to see the currently monitored objects, for debugging
purposes"""
if _global_register_:
for k,v in six.iteritems(_global_register_._registed_by_monitor_key):
logger.warn( '%s : %s'%( k, v ) )