Re: [FWP] Interpreting a columnar text file.

[Chaim Frenkel <chaimf@pobox.com>]

>>>>> "RLS" == Randal L Schwartz <merlyn@stonehenge.com> writes:

RLS> If that's the case, I see what you're doing, and you don't even need
RLS> the x. :)

RLS> $fmt =~ s/\G(\s*)(\S+\s*)/"x".length($1)."A".length($2)/ge;
RLS> Every 'x' after the first will have 0.

Interesting what constitutes defensive programming. :)
Also interesting that your thinking works from the spaces to the data.
Reminds me of those optical illusion drawings. What's foreground
vs. background.

Chaim> Why the \G ?

RLS> Defensive programming, to ensure that I haven't coded the regex wrong
RLS> and skip over data.  This ensures that each new round begins where the
RLS> previous round left off.

This needs more explaination.

How does a the regex go wrong yet the \G will keep it on track, and if
it did go wrong aren't you in bad shape anyway?

Once the regexp matches, and a substitution is done. Isn't there an
implicit \G in there? Can the regexp backtrack behind the replacement?

<chaim>
-- 
Chaim Frenkel					     Nonlinear Knowledge, Inc.
chaimf@pobox.com				               +1-718-236-0183

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