Python中捕捉详细异常信息的代码示例
大家在开发的过程中可能时常碰到一个需求，需要把Python的异常信息输出到日志文件中。
网上的办法都不太实用，下面介绍一种实用的，从Python2.7源码中扣出来的。
废话不说直接上代码，代码不多，注释比较多而已。
importsys,traceback
traceback_template='''Traceback(mostrecentcalllast):
File"%(filename)s",line%(lineno)s,in%(name)s
%(type)s:%(message)s\n'''#Skippingthe"actualline"item
#Alsonote:wedon'twalkallthewaythroughtheframestackinthisexample
#seehg.python.org/cpython/file/8dffb76faacc/Lib/traceback.py#l280
#(Imagineifthe1/0,below,werereplacedbyacalltotest()whichdid1/0.)
try:
1/0
except:
#http://docs.python.org/2/library/sys.html#sys.exc_info
exc_type,exc_value,exc_traceback=sys.exc_info()#mostrecent(ifany)bydefault
'''
Reasonthis_can_bebad:Ifan(unhandled)exceptionhappensAFTERthis,
orifwedonotdeletethelabelson(notmuch)olderversionsofPy,the
referencewecreatedcanlinger.
traceback.format_exc/print_excdothisverything,BUTnotethiscreatesa
tempscopewithinthefunction.
'''
traceback_details={
'filename':exc_traceback.tb_frame.f_code.co_filename,
'lineno':exc_traceback.tb_lineno,
'name':exc_traceback.tb_frame.f_code.co_name,
'type':exc_type.__name__,
'message':exc_value.message,#orseetraceback._some_str()
}
del(exc_type,exc_value,exc_traceback)#Sowedon'tleaveourlocallabels/objectsdangling
#Thisstillisn't"completelysafe",though!
#"Best(recommended)practice:replaceallexc_type,exc_value,exc_traceback
#withsys.exc_info()[0],sys.exc_info()[1],sys.exc_info()[2]
##修改这里就可以把traceback打到任意地方，或者存储到文件中了
printtraceback_template%traceback_details