Thanks all for your ideas. As an alternate way of writing this, so I don't have to have lots of subroutine refs in a big hash structure, I'm now thinking of doing something like this:</code>

use strict;

package Our::Redirects;

sub www_theirsite_com {
    my $url = shift;
    # and transform url here however
}
# allow for alt domain names
*www_theirsite_co_uk = \&www_theirsite_com;


package main;

use URI;

while ( <> ) {
    my $uri = URI->new($_) or
        die "Can't parse URI";
    my $func = lc( $uri->host() );
    $func =~ tr/.-/_/;
    if ( defined &{ "Our::Redirects::$func" } ) {
        &{ \&{ "Our::Redirects::$func" } }($_);
    }
}
[download]

This seems to me to have the advantages of a hash-type construct - i.e. straight-thru mapping - but slightly sugary syntax, particularly for some of the cases which aren't quite as simple as the ones I suggested. Does this seem like a reasonable way to go?

Thanks again