Paul McGuire wrote:
> "proctor" <[EMAIL PROTECTED]> wrote in message
> news:<[EMAIL PROTECTED]>...
> > hello,
> >
> > i hope this is the correct place...
> >
> > i have an issue with some regex code i wonder if you have any insight:
> >
> > ================
>
> There's nothing actually *wrong* wth your regex. The problem is your
> misunderstanding of raw string notation. In building up your regex, do not
> start the string with "r'" and end it with a "'".
>
> def makeRE(w):
> print w + " length = " + str(len(w))
> # reString = "r'" + w[:1]
> reString = w[:1]
> w = w[1:]
> if len(w) > 0:
> for c in (w):
> reString += "|" + c
> # reString += "'"
> print "reString = " + reString
> return reString
>
> Or even better:
>
> def makeRE(w):
> print w + " length = " + str(len(w))
> reString = "|".join(list(w))
> return reString
>
> Raw string notation is intended to be used when the string literal is in
> your Python code itself, for example, this is a typical use for raw strings:
>
> ipAddrRe = r'\d{1,3}(\.\d{1,3}){3}'
>
> If I didn't have raw string notation to use, I'd have to double up all the
> backslashes, as:
>
> ipAddrRe = '\\d{1,3}(\\.\\d{1,3}){3}'
>
> But no matter which way I create the string, it does not actually start with
> "r'" and end with "'", those are just notations for literals that are part
> of your Python source.
>
> Does this give you a better idea of what is happening?
>
> -- Paul
yes! thanks so much.
it does work now...however, one more question: when i type:
rx_a = re.compile(r'a|b|c')
it works correctly!
shouldn't:
rx_a = re.compile(makeRE(test))
give the same result since makeRE(test)) returns the string "r'a|b|c'"
are you saying that the "r'" and "'" are being interpreted differently
in the second case than in the first? if so, how would i go about
using raw string notation in such a circumstance (perhaps if i need to
escape "\b" or the like)? do i have to double up in this case?
proctor.
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