* Winter Christian <[EMAIL PROTECTED]> [2004-06-01 16:31]:
> Another approach:
>
> use re 'eval';
> my $re = qr/(\d{4})(??{ $1>$year?'':'x{1000}' })$/;
>
> Assuming, of course, that $_ never contains a smaller year
> number followed by thousand 'x'es. :-)
You can remove that limitation by replacing 'x{1000}' by '(?!)',
a zero-width negative lookahead, which *always* fails.
Your approach requires multiple regex compilation, too -- the
regex returned by your code is compiled in at run time.
If you do want to go down that route, I'd rather do it like this:
my $re = qr/(\d{4})(?(?{ $1 <= $year })(?!))/;
which uses a conditional subexpression (?(cond)if-true), where
the condition is a Perl expression (?{ $1 <= $year }), to force
failure using the aforementioned (?!), if the condition is true
(which means I must test for less-than-or-equal, where you test
for greater-than).
--
Regards,
Aristotle
"If you can't laugh at yourself, you don't take life seriously enough."
