scanf style parsing

[chasm at atlantis.rift]

>> Regex's are useful and powerful.  But they're also very easy to
>> abuse.  I've actually seen the following Perl code:
>> 
>>     if ($filename =~ /\.txt$/) { ... }
>> 
>> ...
>>
>> or, much more preferably:
>> 
>>     if filename[-4:] == '.txt':
>
>Overall, the Perl code's better.  It didn't have to hard-code the
>length of the string.

	ext = '.txt'
	if filename[-len(ext):] == ext:

	etc...

Julian