##########################################################################
#  
#  Copyright (c) 2012, Image Engine Design Inc. All rights reserved.
#  
#  Redistribution and use in source and binary forms, with or without
#  modification, are permitted provided that the following conditions are
#  met:
#  
#      * Redistributions of source code must retain the above
#        copyright notice, this list of conditions and the following
#        disclaimer.
#  
#      * Redistributions in binary form must reproduce the above
#        copyright notice, this list of conditions and the following
#        disclaimer in the documentation and/or other materials provided with
#        the distribution.
#  
#      * Neither the name of John Haddon nor the names of
#        any other contributors to this software may be used to endorse or
#        promote products derived from this software without specific prior
#        written permission.
#  
#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
#  IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
#  THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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#  
##########################################################################

import sys
import types

def lazyImport( moduleName ) :

	# if the module is already loaded, then just return it
	module = sys.modules.get( moduleName, None )
	if module is not None :
		return module
	
	# load parent module if necessary
	parentModule = None
	parentModuleName = moduleName.rpartition( "." )[0]
	if parentModuleName :
		parentModule = lazyImport( parentModuleName )
		
	module = LazyModule( moduleName )
	sys.modules[moduleName] = module
	return module

class LazyModule( types.ModuleType ) :

	def __init__( self, moduleName ) :
	
		types.ModuleType.__init__( self, moduleName )
	
		self.__loaded = False
	
	def __getattribute__( self, name ) :
	
		if not types.ModuleType.__getattribute__( self, "_LazyModule__loaded" ) :
			# then a reload will trick python into doing the actual import
			reload( self ) 
			self.__loaded = True
			
		return types.ModuleType.__getattribute__( self, name )