[Tutor] Regular Expressions and RFC 822

[Sean 'Shaleh' Perry]

>>
>> So even if you used a regex to match re.compile(r'(\w+):(.+)') you 
>> would still
>> miss the continuation line.  So you almost need a preprocessor which
>> concatenates lines if there is a continuation and when the line is 
>> finished
>> parse it.  Look at the rfc822 module for a better approach and to avoid
>> reinventing the wheel.
> 
> For the record, I really like regular expressions, though I suppose that 
> some people don't.  Perl-compatible regular expression engines can 
> handle the above situation (and many others) but I imagine it uses some 
> sort of preprocessor.  Python's regex implementation is a little 
> different than I'm used to, but I still like 'em (especially in my text 
> editor where I use them all the time to modify my code).
> 

while (<>) {
  if (m/(\w+):(.+)/) {
      $type = $1;
      $data = $2;
  }
}

that code will not handle continuation lines any better than the above python
solution.  Which is the style of code we are discussing.  A common perl idiom
is to slurp a lot of text into a buffer and walk the buffer with a regex.  That
solves the continuation problem for you if you modify your regex to deal with
it.