python try语句如何打印错误行（

import sys
 try:
 a = [1,2]
 print a[3]
 except:
 s=sys.exc_info()
 print "Error '%s' happened on line %d" % (s[1],s[2].tb_lineno)
打印execfile的打印错误行：
try:
 execfile("tprint.py")
 except Exception, info:
 #print info[1]
 print "Error '%s' happened on line %d" % (info[0], info[1][1])
利用反射机制，调用函数，打印被调用方的错误行及错误信息 
 try:
 callfunc.callfunc(myklass,strmethod,params)
 except :
 print '=== STEP ERROR INFO START'
 import traceback
 traceback.print_exc()
 print '=== STEP ERROR INFO END'