urllib2 and exceptions

robean st1999 at gmail.com
Sun Sep 28 21:52:58 CEST 2008


On Sep 28, 12:27 pm, robean <st1... at gmail.com> wrote:
> On Sep 28, 12:11 pm, "Chris Rebert" <c... at rebertia.com> wrote:
>
>
>
> > On Sun, Sep 28, 2008 at 11:03 AM, robean <st1... at gmail.com> wrote:
> > > Hi everyone,
>
> > > I have a question about using urllib2.
>
> > > I like urllib2 better than urllib at least in part because it has more
> > > elaborate support for handling errors: there is built in support for
> > > URLError (for faulty urls) and HTTPError (for http errors that might
> > > originate from, say, passing an invalid stock-ticker in the program
> > > below).  However I can get neither to work.  I'm attaching below the
> > > (very short) code: can anyone point out what I'm doing wrong?
>
> > > Now, if I replace the URLError and HTTPError with IOError (the class
> > > from which both URLError and HTTPError inherit), the program works
> > > fine. Why is it that I can call the generic IOError class, but none of
> > > the Error classes derived from that? These are clearly defined in the
> > > urllib2 manual. Very confused...
>
> > > Here's the code:
>
> > > import urllib2
>
> > > # read stock information from yahoo finance for Traget (TGT)
> > > goodTicker = 'TGT' # program works with this
> > > badTicker = 'TGTttttttt' # python doesn't understand either HTTPError
> > > or URLError with this
>
> > > url = "http://ichart.finance.yahoo.com/table.csv?s=" + badTicker
>
> > > try:
> > >        handle = urllib2.urlopen(url)
>
> > > # this does not work
> > > except HTTPError, e:
> > >        print "There was an http error"
> > >        print e
>
> > > # this also does not work
> > > except URLError, e:
> > >        print "There is a problem with the URL"
> > >        print e
> > >        exit(1)
>
> > > #this works
> > > except IOError, e:
> > >        print "You have an IOError"
> > >        print e
>
> > > text = handle.readlines()[:20]
> > > for line in text:
> > >        print line
>
> > > --
> > >http://mail.python.org/mailman/listinfo/python-list
>
> > My Python begs to differ:
>
> > #tmp.py
> > import urllib2
>
> > badTicker = 'TGTttttttt'
> > url = "http://ichart.finance.yahoo.com/table.csv?s=" + badTicker
>
> > try:
> >     handle = urllib2.urlopen(url)
>
> > except urllib2.HTTPError, e:
> >     print "There was an http error"
> >     print e
>
> > except urllib2.URLError, e:
> >     print "There is a problem with the URL"
> >     print e
>
> > except urllib2.IOError, e:
> >     print "You have an IOError"
> >     print e
>
> > #in the shell
> > $ python -V
> > Python 2.5.1
> > $ python Desktop/tmp.py
> > There was an http error
> > HTTP Error 404: Not Found
>
> > Are you using an outdated version of Python perhaps?
>
> > Regards,
> > Chris
>
> > --
> > Follow the path of the Iguana...http://rebertia.com
>
> Then I expect that it is most likely my version of python that is
> causing the problem. I'm using 2.5.2.

Actually, the problem seems to be that IOError is in my namespace, but
the other error classes are not. So,

   except HTTPError, etc.

fails, but

   except urllib2.HttpError, etc.

works fine. Now, I still don't understand why these classes shouldn't
automatically work....



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