Steve Newcomb <s...@coolheads.com> added the comment:
I'm very grateful for your time and attention, and sorry to have distracted
you. You're correct when you say:
Steven D'Aprano: ...the rightmost alternative matches from position 1 of the
text, while the leftmost alternative doesn't match until position 8. So
starting from position 0, the IPV6 check matches first, and so wins.
I see now that what I was trying to do is simply not possible. I was looking
for a way to do a kind of hat trick: to keep a matched substring ("::ffff:")
out of matchObject.group(0). I guess I just don't get to do that.
It would be a nice feature to add: a "consume-and-forget" or "suppress"
extension group type. Non-capturing groups forget about themselves, but they
don't suppress their matched contents. It's a nice thing to be able to do
because some software accepts regular expressions as configuration items but
doesn't allow configuration of selection among the groups that may appear
within it. (I admit there aren't many occasions when suppression of substrings
from group(0) is really necessary, but I think they do occur.)
----------
stage: -> resolved
status: open -> closed
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue35496>
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