YANRQ (yet another regex question)

[Mats Kindahl]

Tim Peters <tim.one at comcast.net> writes:

> [Michael George Lerner]
> > I have a regular expression that looks vaguely like this:
> >
> > r = re.compile(r'''(?P<start>start)(?P<foo>   foo)(?P<end>end)''')
> >
> > but the middle pattern isn't quite what I want.  I know that foo
> > will be a string that is seven characters long and contains 'foo'
> > surrounded by spaces.  That is, it could be any of these:
> >
> > 'foo    '
> > ' foo   '
> > '  foo  '
> > '   foo '
> > '    foo'
> >
> > I'd like to rewrite my regular expression to match any of these,
> > and I'd really rather not write it all out like this:
> >
> > (?P<foo>(foo    | foo   |  foo  |   foo |    foo|)
> 
> That will also match an empty string (remove the last vertical bar; ditto
> the 2nd left paren).
> 
> > Is there some easy way to do this that I've overlooked?
> 
> You already found an easy way <wink>.  If you ask whether there's an easier
> way, the answer is no.

Depending on the definition of easy, this is the alternative I would
use. 

	r = re.compile(r'(?P<foo>(?=.{7}) *foo *)')
	
Of course, your milage may wary.

-- 
Mats Kindahl, IAR Systems, Sweden

Any opinions expressed are my own, not my company's.