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import weakref

import maya.cmds
import maya.OpenMaya

import IECore
import IECoreMaya

class CallbackIdTest( IECoreMaya.TestCase ) :

	def test( self ) :

		# callback function just counts the number of times it has been invoked
		CallbackIdTest.numCalls = 0
		def callback( node, name, userData ) :

			CallbackIdTest.numCalls += 1

		# make a sphere and get the MObject from it
		sphere = maya.cmds.sphere()[0]
		s = maya.OpenMaya.MSelectionList()
		s.add( sphere )
		o = maya.OpenMaya.MObject()
		s.getDependNode( 0, o )

		# attach a name changed callback
		c = IECoreMaya.CallbackId( maya.OpenMaya.MNodeMessage.addNameChangedCallback( o, callback ) )

		# check that the callback is invoked
		self.assertEqual( CallbackIdTest.numCalls, 0 )
		sphere = maya.cmds.rename( sphere, sphere + "Different" )
		self.assertEqual( CallbackIdTest.numCalls, 1 )

		# delete the CallbackId object and make sure the callback is removed and therefore not invoked any more
		del c
		sphere = maya.cmds.rename( sphere, sphere + "DifferentAgain" )
		self.assertEqual( CallbackIdTest.numCalls, 1 )

		# also check that maya isn't holding onto any unecessary references to the callback function.
		w = weakref.ref( callback )
		del callback
		self.assertEqual( w(), None )

if __name__ == "__main__":
	IECoreMaya.TestProgram()
