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Re: Need regex help

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From:
ToddAndMargo
Date:
September 16, 2018 07:33
Subject:
Re: Need regex help
Message ID:
62f1fee1-9788-c690-257d-7acdb698f1e7@zoho.com
On 09/15/2018 07:32 PM, Larry Wall wrote:
> On Sat, Sep 15, 2018 at 06:45:33PM -0700, ToddAndMargo wrote:
> : Hi All,
> :
> : I have been doing a bunch with regex's lately.
> : I just throw them out based on prior experience
> : and they most all work now.  I only sometimes have to
> : ask for help.  (The look forward () feature
> : is sweet.)
> :
> : Anyway, I have been using regex switches without
> : knowing why. So
> :
> : What is the difference between
> :
> : \N
> 
> That is a character that is not any of the valid \n characters.
> 
> : :\N
> 
> That is not a thing.  That is a colon, which causes the previous thing
> to not backtrack (if it would), followed by a \N (see above).
> 
> : <:\N>
> 
> That is not a thing.  In fact, it's a syntax error.
> 
> : <<\:N>>
> 
> That also is not a thing.  That is a left word boundary <<, followed by
> \:, which matches a quote literally because it's backslashed, followed
> by an N, which also matches literally, followed by the right word
> boundary >>.  As a pattern, it is impossible for the combination to match,
> since, while >> can match after a literal N, a << cannot match before a colon.
> 
> : And why would I choose one over the other (what
> : are they called out for)?
> 
> I would never choose any of them, apart from \N.  Where are you getting
> this craptastic list from?
> 
> Larry
> 

Hi Larry,

Well.  I will have to go through my question with a fine
toothed comb and create a keeper tutorial for what I
come up with.  And in the process, I will no doubt trip
across a lot of stuff I got wrong.

It may be two weeks before I get back -- I have to finish
my company's federal taxes -- but I will get back with whagt I
come up with.

And to answer your question:  I got some of this stuff
from

https://docs.perl6.org/language/regexes#index-entry-regex_%3C%3Aproperty%3E-Unicode_properties

some from context (what I have seen), and

Well, the rest of it from, shall we say pulled out of
my ear.

Into everyone's life a little humiliation must fall.

Thank you for all your help with this.

-T

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