Python 尝试除了最后

Question

看来我还不太了解异常处理。我不知所措:( 以下代码有时会返回此错误:

File "applications/pingback/modules/plugin_h_pingback.py", line 190, in ping
    db(table.id==id_).update(status=status)
UnboundLocalError: local variable 'status' referenced before assignment

我希望 status 总是被赋予一个值。会不会是抛出了其他一些异常(可能在内部 try 中)并且 finally 掩盖了它？

...
try:
    server_url = self._get_pingback_server(target)
except PingbackClientError, e:
    status = e.message
else:
    try:
        server = xmlrpclib.ServerProxy(server_url)
        status = server.pingback.ping(self.source, target)
    except xmlrpclib.Fault, e:
        status = e
finally:
    db(table.id==id_).update(status=status) # <-- UnboundLocalError
...

谢谢楼主

Answer 1

您的代码并不总是为状态分配某些内容。我可以看到几种可能无法分配状态的方式，我在下面突出显示了它们:

try:
    server_url = self._get_pingback_server(target)
except PingbackClientError, e:
    # If evaluating `e.message` raises an exception then status is not set.
    status = e.message  # <--- here
else:
    try:
        # If either of these two lines fails with something other than
        # xmlrcplib.Fault, then status is not set.
        server = xmlrpclib.ServerProxy(server_url)             # <--- here
        status = server.pingback.ping(self.source, target)     # <--- here
    # If xmlrpclib.Fault is not defined status is not set.
    except xmlrpclib.Fault, e:                                 # <--- here
        status = e
finally:
    db(table.id==id_).update(status=status)

我怀疑错误最有可能发生在内部 try block 中，您只捕获 xmlrpclib.Fault 而不是其他类型的异常。