python 停止执行用 execfile 调用的脚本
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Stop execution of a script called with execfile
提问by JcMaco
Is it possible to break the execution of a Python script called with the execfile function without using an if/else statement? I've tried exit(), but it doesn't allow main.pyto finish.
是否可以在不使用 if/else 语句的情况下中断使用 execfile 函数调用的 Python 脚本的执行？我试过了exit()，但它不允许main.py完成。
# main.py
print "Main starting"
execfile("script.py")
print "This should print"
# script.py
print "Script starting"
a = False
if a == False:
# Sanity checks. Script should break here
# <insert magic command>
# I'd prefer not to put an "else" here and have to indent the rest of the code
print "this should not print"
# lots of lines below
回答by Alex Martelli
maincan wrap the execfileinto a try/exceptblock: sys.exitraises a SystemExit exception which maincan catch in the exceptclause in order to continue its execution normally, if desired. I.e., in main.py:
main可以将 包装execfile到try/except块中：如果需要，sys.exit会引发 SystemExit 异常，该异常main可以在except子句中捕获以继续正常执行。即，在main.py：
try:
execfile('whatever.py')
except SystemExit:
print "sys.exit was called but I'm proceeding anyway (so there!-)."
print "so I'll print this, etc, etc"
and whatever.pycan use sys.exit(0)or whatever to terminate its ownexecution only. Any other exception will work as well as long as it's agreed between the source to be execfiled and the source doing the execfilecall -- but SystemExitis particularly suitable as its meaning is pretty clear!
并且whatever.py只能使用sys.exit(0)或任何东西来终止它自己的执行。只要是execfiled 的来源与进行execfile调用的来源之间达成一致，任何其他异常都可以正常工作——但SystemExit特别合适，因为它的含义非常清楚！
回答by Matthew Flaschen
# script.py
def main():
print "Script starting"
a = False
if a == False:
# Sanity checks. Script should break here
# <insert magic command>
return;
# I'd prefer not to put an "else" here and have to indent the rest of the code
print "this should not print"
# lots of lines bellow
if __name__ == "__main__":
main();
I find this aspect of Python (the __name__== "__main__", etc.) irritating.
我发现 Python 的这方面（__name__== "__main__”等）很烦人。
回答by S.Lott
What's wrong with plain old exception handling?
普通的旧异常处理有什么问题？
scriptexit.py
脚本退出.py
class ScriptExit( Exception ): pass
main.py
主文件
from scriptexit import ScriptExit
print "Main Starting"
try:
execfile( "script.py" )
except ScriptExit:
pass
print "This should print"
script.py
脚本文件
from scriptexit import ScriptExit
print "Script starting"
a = False
if a == False:
# Sanity checks. Script should break here
raise ScriptExit( "A Good Reason" )
# I'd prefer not to put an "else" here and have to indent the rest of the code
print "this should not print"
# lots of lines below
