old_contents: ##########################################################################
  #
  #  Copyright (c) 2012, John Haddon. All rights reserved.
  #  Copyright (c) 2013, 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
  #  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  #  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  #  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  #  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  #  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  #  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  #  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  #  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  #
  ##########################################################################
  
  import Gaffer
  import GafferImage
  
  # add plugs to the preferences node
  
  preferences = application.root()["preferences"]
  preferences["cache"] = Gaffer.CompoundPlug()
  preferences["cache"]["enabled"] = Gaffer.BoolPlug( defaultValue = True )
  preferences["cache"]["memoryLimit"] = Gaffer.IntPlug( defaultValue = Gaffer.ValuePlug.getCacheMemoryLimit() / ( 1024 * 1024 ) )
  preferences["cache"]["imageReaderMemoryLimit"] = Gaffer.IntPlug( defaultValue = GafferImage.ImageReader.getCacheMemoryLimit() )
  
  # update cache settings when they change
  
  def __plugSet( plug ) :
  
  	if plug.relativeName( plug.node() ) != "cache" :
  		return
  
  	memoryLimit = plug["memoryLimit"].getValue() * 1024 * 1024
  	imageReaderMemoryLimit = plug["imageReaderMemoryLimit"].getValue()
  	if not plug["enabled"].getValue() :
  		memoryLimit = 0
  		imageReaderMemoryLimit = 0
  
  	Gaffer.ValuePlug.setCacheMemoryLimit( memoryLimit )
  	GafferImage.ImageReader.setCacheMemoryLimit( imageReaderMemoryLimit )
  
  application.__cachePlugSetConnection = preferences.plugSetSignal().connect( __plugSet )
  
new_contents: ##########################################################################
  #
  #  Copyright (c) 2012, John Haddon. All rights reserved.
  #  Copyright (c) 2013, 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
  #  PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  #  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  #  EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  #  PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  #  PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  #  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  #  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  #  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  #
  ##########################################################################
  
  import Gaffer
  import GafferImage
  
  # add plugs to the preferences node
  
  preferences = application.root()["preferences"]
  preferences["cache"] = Gaffer.CompoundPlug()
  preferences["cache"]["enabled"] = Gaffer.BoolPlug( defaultValue = True )
  preferences["cache"]["memoryLimit"] = Gaffer.IntPlug( defaultValue = Gaffer.ValuePlug.getCacheMemoryLimit() / ( 1024 * 1024 ) )
  preferences["cache"]["imageReaderMemoryLimit"] = Gaffer.IntPlug( defaultValue = GafferImage.ImageReader.getCacheMemoryLimit() )
  
  Gaffer.Metadata.registerPlugValue(
      preferences["cache"]["memoryLimit"],
      "description",
      """
      Controls the memory limit for Gaffer's ValuePlug cache.
      """
  )
  
  Gaffer.Metadata.registerPlugValue(
      preferences["cache"]["imageReaderMemoryLimit"],
      "description",
      """
      Controls the memory limit for the OpenImageIO cache that the ImageReader node uses.
      """
  )
  
  
  # update cache settings when they change
  
  def __plugSet( plug ) :
  
  	if plug.relativeName( plug.node() ) != "cache" :
  		return
  
  	memoryLimit = plug["memoryLimit"].getValue() * 1024 * 1024
  	imageReaderMemoryLimit = plug["imageReaderMemoryLimit"].getValue()
  	if not plug["enabled"].getValue() :
  		memoryLimit = 0
  		imageReaderMemoryLimit = 0
  
  	Gaffer.ValuePlug.setCacheMemoryLimit( memoryLimit )
  	GafferImage.ImageReader.setCacheMemoryLimit( imageReaderMemoryLimit )
  
  application.__cachePlugSetConnection = preferences.plugSetSignal().connect( __plugSet )
  
subject: Add tooltip to cache preferences plugs