python try语句如何打印错误行

打印当前.py文件错误行：

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'