Can an except block of python have 2 conditions simultaneously? - python-3.x

Question

I was trying to learn stock prediction with the help of this github project. but when I run the main.py file given in the repository, via the cmd. I encountered an error
File "/Stock-Predictor/src/tweetstream/streamclasses.py", line 101
except urllib2.HTTPError, exception:
^
SyntaxError: invalid syntax
The below given code is part of a PyPi module named tweetstreami.e. named as tweetstream/streamclasses.py. Which while implementing in a Twitter sentiment analysis project gave the error
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

The second item in the except is an identifier used in the body of the exception to access the exception information. The try/except syntax changed between Python 2 and Python 3 and your code is the Python 2 syntax.
Python 2 (language reference):
try:
...
except <expression>, <identifier>:
...
Python 3 (language reference, rationale):
try:
...
except <expression> as <identifier>:
...
Note that can be a single exception class or a tuple of exception classes to catch more than one type in a single except clause, so to answer your titled question you could use the following to handle more than one possible exception being thrown:
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

Use...
Try: #code here
Except MyFirstError: #exception handling
Except AnotherError: #exception handling
You can repeat this many times