python的except块可以同时有2个条件吗？

Question

我试图借助 github project 学习股票预测。但是当我通过cmd 运行存储库中给出的main.py 文件时。我遇到了一个错误

File "/Stock-Predictor/src/tweetstream/streamclasses.py", line 101
    except urllib2.HTTPError, exception:
                            ^
SyntaxError: invalid syntax

下面给出的代码是一个名为 tweetstreami.e. 的 PyPi 模块的一部分。命名为tweetstream/streamclasses.py。在 Twitter 情绪分析项目中实施时出现错误

import time
import urllib
import urllib2
import socket
from platform import python_version_tuple
import anyjson

from . import AuthenticationError, ConnectionError, USER_AGENT 

class BaseStream(object):
    """A network connection to Twitters streaming API
    :param username: Twitter username for the account accessing the API.
    :param password: Twitter password for the account accessing the API.
    :keyword count: Number of tweets from the past to get before switching to
      live stream.
    :keyword url: Endpoint URL for the object. Note: you should not
      need to edit this. It's present to make testing easier.
    .. attribute:: connected
        True if the object is currently connected to the stream.
    .. attribute:: url
        The URL to which the object is connected
    .. attribute:: starttime
        The timestamp, in seconds since the epoch, the object connected to the
        streaming api.
    .. attribute:: count
        The number of tweets that have been returned by the object.
    .. attribute:: rate
        The rate at which tweets have been returned from the object as a
        float. see also :attr: `rate_period`.
    .. attribute:: rate_period
        The amount of time to sample tweets to calculate tweet rate. By
        default 10 seconds. Changes to this attribute will not be reflected
        until the next time the rate is calculated. The rate of tweets vary
        with time of day etc. so it's useful to set this to something
        sensible.
    .. attribute:: user_agent
        User agent string that will be included in the request. NOTE: This can
        not be changed after the connection has been made. This property must
        thus be set before accessing the iterator. The default is set in
        :attr: `USER_AGENT`.
    """

    def __init__(self, username, password, catchup=None, url=None):
        self._conn = None
        self._rate_ts = None
        self._rate_cnt = 0
        self._username = username
        self._password = password
        self._catchup_count = catchup
        self._iter = self.__iter__()

        self.rate_period = 10  # in seconds
        self.connected = False
        self.starttime = None
        self.count = 0
        self.rate = 0
        self.user_agent = USER_AGENT
        if url: self.url = url

    def __enter__(self):
        return self

    def __exit__(self, *params):
        self.close()
        return False

    def _init_conn(self):
        """Open the connection to the twitter server"""
        headers = {'User-Agent': self.user_agent}

        postdata = self._get_post_data() or {}
        if self._catchup_count:
            postdata["count"] = self._catchup_count

        poststring = urllib.urlencode(postdata) if postdata else None
        req = urllib2.Request(self.url, poststring, headers)

        password_mgr = urllib2.HTTPPasswordMgrWithDefaultRealm()
        password_mgr.add_password(None, self.url, self._username, self._password)
        handler = urllib2.HTTPBasicAuthHandler(password_mgr)
        opener = urllib2.build_opener(handler)

        try:
            self._conn = opener.open(req)

        except urllib2.HTTPError, exception:  #___________________________problem here
            if exception.code == 401:
                raise AuthenticationError("Access denied")
            elif exception.code == 404:
                raise ConnectionError("URL not found: %s" % self.url)
            else:  # re raise. No idea what would cause this, so want to know
                raise
        except urllib2.URLError, exception:
            raise ConnectionError(exception.reason)

Answer 1

except 中的第二项是在异常主体中用于访问异常信息的标识符。 try/except 语法在 Python 2 和 Python 3 之间发生了变化，您的代码是 Python 2 语法。

Python 2 (language reference)：

try:
    ...
except <expression>, <identifier>:
    ...

Python 3（language reference，rationale）：

try:
    ...
except <expression> as <identifier>:
    ...

请注意，可以是单个异常类或异常类元组，以在单个 except 子句中捕获多个类型，因此要回答您的标题问题，您可以使用以下内容来处理多个可能的异常抛出：

try:
    x = array[5]  # NameError if array doesn't exist, IndexError if it is too short
except (IndexError,NameError) as e:
    print(e)  # which was it?

Answer 2

使用...

Try: #code here

Except MyFirstError: #exception handling

Except AnotherError: #exception handling

你可以重复多次