:- object(metric(_Town)).
:- info([
author is 'Paulo Moura',
version is 1.0,
date is 2000/4/22,
comment is '.',
parnames is ['Town'],
source is 'Example adopted from the Francis G. McCabe L&O documentation.']).
:- public(less/2).
less((Town1, _), (Town2, _)):-
parameter(1, Town),
Town::crow_flies(Town1, Distance1),
Town::crow_flies(Town2, Distance2),
Distance1 < Distance2.
:- end_object.
