Handling HasNoEffect state on a plugin node.

If you're writing a Maya plugin node, you might want to handle the case where the user sets the node state to HasNoEffect. The state is an input attribute that is implicitly defined for any node. You can query it in a similar way to any other input attribute:

stateHnd = dataBlock.inputValue( self.state ) #MDataHandle
if stateHnd.asInt() == 1 :
inMeshHnd = dataBlock.inputValue( self.inMesh )
outMeshHnd = dataBlock.outputValue( self.outMesh )
inMeshObj = inMeshHnd.asMesh() # MObject
outMeshHnd.setMObject( inMeshObj )
dataBlock.setClean( plug )
return OpenMaya.MStatus.kSuccess