== Turning off HTTP basic authentication in urllib

Python's [[urllib module
http://www.python.org/doc/current/lib/module-urllib.html]] conveniently
handles a great many bits of fetching URLs for you, including HTTP basic
authentication. Unfortunately it does this by pausing everything to 'ask
the user for the required information on the controlling terminal' (to
more or less quote from the documentation). This is generally not the
most useful behavior in the world, and can even be rather disconcerting.

(A more sensible default behavior would have been to either raise an
exception or return a HTTP 'authentication required' status.)

As a result, all of my urllib-using programs start off by neutering this
behavior, so that if I ask them to deal with a stray URL that requires
HTTP basic authentication they'll just fail. To do this, you need to
subclass FancyURLopener and supply your own ((get_user_passwd)) routine
that does nothing:

>  from urllib import FancyURLopener
>  
>  class MyOpener(FancyURLopener):
>    def get_user_passwd(self, h, r, c_c = 0)
>      return None, None

This is covered in the urllib documentation, sort of, but not even the
urllib docstrings tell you what the return value should be. Apparently
you are just supposed to read the source.

(Technically you can supply a do-nothing ((prompt_user_passwd)) routine
instead, with the same effect, but I prefer to just neuter the whole
thing.)

This is not the only peculiar thing urllib does. For another example, it
turns basically every problem into _IOError_ exceptions, generally in
blithe disregard of their standard format. (And of course it is now far
too late to fix this, because it would break backwards compatibility for
everyone who has carefully worked around this.)

There's the [[urllib2 module
http://www.python.org/doc/current/lib/module-urllib2.html]] as an
alternative, but the length of its documentation makes my eyes glaze
over. However, on some testing it seems to be reasonably simple to use,
and as a bonus it does the right thing with HTTP basic authentication. I
suspect that I should start switching my code over, and certainly use it
for anything new I do.

(I still use urllib because I started with Python in the 1.5 days, when
there was no urllib2. Technically we still have some machines with
1.5.2, but on those machines we just use a locally built version of
2.3.4.)