Another nntplib Question

[Thomas Jollans]

On 06/10/2010 12:56 AM, Anthony Papillion wrote:
> Hello Everyone,
> 
> Thanks to help from this group, my statistical project is going very
> well and I'm learning a LOT about Python as I go. I'm absolutely
> falling in love with this language and I'm now thinking about using it
> for nearly all my projects.
> 
> I've run into another snag with nntplib I'm hoping someone can help me
> with. I'm trying to get a list of newsgroups from the server. The
> documentation for the list() method tells me it returns a response
> (string) and a list (tuple).
> 
> The list tuple contains the following: groupname, last, first, flag.
> So, thinking I could access the group name in that list like this
> ThisGroup = groupname[1].
> 
> Now, along those lines, I am wanting to retrieve some information
> about each group in the list so I thought I could do this:
> 

Hi again ^^
Let's have a look at what your code actually does. I'm not going to
check the docs myself just now.

> resp, groupinfo = server.list()
okay, looks fine. so groupinfo would, as per what you said earlier, be
in this format:

 [ (groupname1, last1, first1, flag1),
   (groupname2, last2, first2, flag2),
   ... ]

> group = (info[1] for info in groupinfo)

Here, you're using a generator expression to create a generator object
which will yield info[1] if you loop over it. So after this line you
could do this:

for x in group:
    print (x)

and it would print every "last" field from above. info[1] is NOT the
first item in info, but the second one, since Python sequences are
zero-indexed. groupname would be info[0]. (it looks as though you might
have forgotten this)

> resp, count, first, last, name = server.group(group)

Here, you're passing the generator object to the server.group method. It
probably wasn't expecting that.

> 
> But Python throws a TypeError and tells me I "can't concatenate str
> and generator objects'.

This almost certainly originated in the NNTPlib code. It expected the
object you passed (a generator object) to be a string and did something like
  send("BEGINNING OF REQUEST LINE"+thing_I_got_passed)
which, obviously, can't work if you don't pass a string (the group name
is expected, I presume)

So, what you probably want to do would look something like this:

resp, groupinfos = server.list()
for info in groupinfos:
    resp, count, first, last, name = server.group(info[0])
    # do something with the info here.

> 
> What am I doing wrong? I've been banging my head on this for a few
> hours and simply can't get it right. I've even googled for an example
> and couldn't find one that showed how to deal with this.
> 
> Can anyone help?
> 
> Thanks in advance!
> Anthony