Hi M,
> I'm horrified by the code repetition. Doesn't Perl allow 'functions'?
Yes, that's those
sub foo {
...
}
you see.
It can also hold a regexp in a variable so a `$pid_regexp' could be
defined once and used repeatedly.
$ perl -e '
> $re = qr/^(food|drink|famine)\d*$/;
> while (<>) {
> /$re/ and print "$. $_";
> }
> '
abc
food
2 food
drink42
3 drink42
xyz
$
BTW, given your private email, you might be interested to know the
Regular Expressions, of which regexps are an extension, are essentially
a "little language" for describing a regular grammar, level 3 in
Chomsky's hierarchy. These are grammars that can be matched with a
finite-state automaton, and implementations are either
non-deterministic, like Perl's, or deterministic, like Go's. As such,
they're a succinct way of expressing many text matching problems, just
as BNF is a convenient method for programming language grammars. It's
interesting to compare the simple one above to the alternative long-hand
imperative programming form.
--
Cheers, Ralph.
https://plus.google.com/+RalphCorderoy
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