change a string conditional

[Rich Harkins]

On Thursday 09 May 2002 01:02 pm, obantec support wrote:
> Hi
>
> I need to a piece of python code that will take a string which may or may
> not begin with www and change it to lists.
>
> eg. www.domain.com becomes lists.domain.com
> but if domain1.com (no www) the it still becomes lists.domain1.com
>
> an example of a pattern match will be enough.(I do a bit of perl but never
> done any python)
>
> mark

Assuming that you always want to preserve the last two segments of the 
hostname (the y and z in x.y.z and w.x.y.z) you don't need pattern matches at 
all...

def translate(host,prefix):
    """
    Removes everything from host before the main domain name and places
    prefix there instead.  
    """
    # One line version: return '.'.join(['lists']+host.split('.')[-2:])
    parts=host.split('.')[-2:]	# Break into parts
    parts=[prefix]+parts		# Stick prefix in front of parts.
    return '.'.join(parts)		# Join it all together with '.''s in between.

print translate('www.domain.com','lists')
print translate('domain.com','lists')
print translate('a.weird.subdomain.domain.com','lists')

(The output is):
lists.domain.com
lists.domain.com
lists.domain.com

I think that's what you were asking for - or did I miss it?

Rich