>>>>> "BC" == Bob Clancy <[EMAIL PROTECTED]> writes:
BC> Hello,
BC> At our recent Boston.pm social meeting, I mentioned this
BC> particular feature of Perl regex's to a few people, and they
BC> didn't know about it. I learned about it somewhere in a book.
BC> (My recollection is that it is not documented under regex (or
BC> regexp?).
BC> [EMAIL PROTECTED] bclancy]$ showfunc showfunc
BC> showfunc ()
BC> {
BC> set | perl -ne 'print if m#^'$*' \(\)# .. m#^}$#'
that is the range operator and it is documented in perlop. it has a list
form which generates lists from low to high. the scalar form which you
see above is a logical flip flop (many call it the flipflop
operator). yes, the scalar form is not well known or used a lot. i have
used it several time when parsing out multiple line sections when
reading line by line. but now i slurp in the file and use m//g to grab
all the sections. simpler and faster. but scalar .. has many other uses.
on a side note, don't use # for m// delimiters. i find it very hard to
read and it confuses people with comments. the best alternate delimiter
(recommended by PBP and myself :) is {}. it allows for nested matched
pairs of {} too. but the above regex doesn't have any / in it so it
doesn't need an alternate delimiter. stick with // whenever you
can. using alternate delims is meant for when you have / as data in the
regex.
BC> }
BC> [EMAIL PROTECTED] bclancy]$
BC> Until I saw this Perl pattern shown above, I used to use awk, and
BC> set a variable upon matching the first regex, and clearing a
BC> variable upon seeing the second regex, then printing lines when
BC> the variable was set. For example:
BC> [EMAIL PROTECTED] CTS4.run.2008-06-27T13_58_45,500]$ showfunc awkfunc
BC> awkfunc ()
BC> {
BC> set | awk 'BEGIN {p=0}; /^'$*' ()/{p=1}; (p); /^}$/{p=0}'
amusing since awk supports the .. concept and perl stole from awk. my
awkfu is extremely corroded but iirc, you just have pair of patterns
separated with , before the block of code. something like this:
/^'$*' ()/, /^}$/ {do something here like print}
that is easier than the perl equiv. i don't use awk at all but as larry
says there have to be some things that awk is better at than perl. :)
uri
--
Uri Guttman ------ [EMAIL PROTECTED] -------- http://www.sysarch.com --
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