parentAddedMsgCmd.py

#-
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#+

# import maya
# maya.cmds.loadPlugin("parentAddedMsgCmd.py")
# maya.cmds.spParentAddedMsg()

import sys
import maya.OpenMaya as OpenMaya
import maya.OpenMayaMPx as OpenMayaMPx

kPluginCmdName = "spParentAddedMsg"

messageId = 0
messageIdSet = False

def removeCallback(id):
        try:
                OpenMaya.MMessage.removeCallback( id )
        except:
                sys.stderr.write( "Failed to remove callback\n" )
                raise

def dagParentAddedCallback( child, parent, clientData ):
        print "dagParentAddedCallback..."
        print "\tchild %s" % child.fullPathName()
        print "\tparent %s" % parent.fullPathName()
        print "\tclient data %s" % clientData

def createParentAddedCallback(stringData):
        # global declares module level variables that will be assigned
        global messageIdSet
        try:
                id = OpenMaya.MDagMessage.addParentAddedCallback( dagParentAddedCallback, stringData )
        except:
                sys.stderr.write( "Failed to install dag parent added callback\n" )
                messageIdSet = False
        else:
                messageIdSet = True
        return id

# command
class scriptedCommand(OpenMayaMPx.MPxCommand):
        def __init__(self):
                OpenMayaMPx.MPxCommand.__init__(self)
        def doIt(self,argList):
                global messageId
                if ( messageIdSet ):
                        print "Message callaback already installed"
                else:
                        print "Installing parent added callback message"
                        messageId = createParentAddedCallback( "_noData_" )

# Creator
def cmdCreator():
        return OpenMayaMPx.asMPxPtr( scriptedCommand() )
        
# Initialize the script plug-in
def initializePlugin(mobject):
        mplugin = OpenMayaMPx.MFnPlugin(mobject)
        try:
                mplugin.registerCommand( kPluginCmdName, cmdCreator )
        except:
                sys.stderr.write( "Failed to register command: %s\n" % name )
                raise

# Uninitialize the script plug-in
def uninitializePlugin(mobject):
        # Remove the callback
        if ( messageIdSet ):
                removeCallback( messageId )
        # Remove the plug-in command
        mplugin = OpenMayaMPx.MFnPlugin(mobject)
        try:
                mplugin.deregisterCommand( kPluginCmdName )
        except:
                sys.stderr.write( "Failed to unregister command: %s\n" % kPluginCmdName )
                raise