> Mailing-List: contact [EMAIL PROTECTED]; run by ezmlm
> Date: Tue, 10 Dec 2002 21:07:34 -0500
> From: Adam Turoff <[EMAIL PROTECTED]>
> Cc: [EMAIL PROTECTED]
> Content-Disposition: inline
> X-SMTPD: qpsmtpd/0.20, http://develooper.com/code/qpsmtpd/
>
> On Tue, Dec 10, 2002 at 03:38:58PM -0800, Rich Morin wrote:
> > On occasion, I have found it useful to cobble up a "little language"
> > that allows me to generate a list of items, using a wild-card or some
> > other syntax, as:
> >
> > foo[0-9][0-9] yields foo00, foo01, ...
> >
> > I'm wondering whether Perl should have a similar capability, using REs.
>
> Dominus has an example of an 'odometer' written using closures. If
> you want to specify a simple sequence like this using a regex, then
> you need to parse the regex (but in reverse).
>
> Alternatively, you could write a generic odometer generator generator
> that takes a series of scalars and lists:
>
> my $generator = make_generator('foo', [0..9], [0..9]);
>
> while ($_ = $generator->()) {
> ## progressively generate foo00, foo01, ...
> }
>
> Z.
It only differentiates between arrays an non-, but it would be trivial
to add other semantics, if you figure out what they actually are.
sub make_generator(*@pats) {
return unless @pats;
given shift @pats -> $pattern {
when Array {
for @$pattern -> $item {
my $generator = make_generator(@pats);
yield $item ~ $_ for <$generator>;
}
}
otherwise {
my $generator = make_generator(@pats);
yield $pattern ~ $_ for <$generator>;
}
}
}
You'd use it just like I did in the sub, as an iterator.
This would have been dastardly complex without corouties. :-)
Luke
