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import maya.cmds as cmds
import maya.mel as mel

def lengthOfCurve(dagPathToCurve):
	"""
	Assume that the Shape path is given, error checking is for upstream
	"""
	import maya
	numSpans = cmds.getAttr("%s.spans" % dagPathToCurve)
	arcLengthTemp= cmds.arcLengthDimension("%s.u[%s]" % (dagPathToCurve,numSpans))
 
	nodeParent = cmds.listRelatives(arcLengthTemp,parent=True)
	curveLength = cmds.getAttr ("%s.al" % arcLengthTemp)
	cmds.delete(nodeParent)
	return curveLength
 
 
for i in cmds.ls(selection=True):
	shapeNodes = cmds.listRelatives(i,shapes=True)
	for shape in shapeNodes:
		if cmds.nodeType(shape) == "nurbsCurve":
			print "Curve: %s is %s units long" % (shape, lengthOfCurve(shape))
		else:
			print "Wrong: %s is a %s" % (shape, cmds.nodeType(shape))