NAME

GIS::Distance::Formula - Formula base class.

DESCRIPTION

This is the parent class for all GIS::Distance formula classes such as those listed at "FORMULAS" in GIS::Distance.

To author your own formula class:

            

              
              
package My::Formula;
use parent 'GIS::Distance::Formula';
sub _distance {
    my ($lat1, $lon1, $lat2, $lon2) = @_;
     
    # ...
     
    return $kilometers;
}
1;
            
          

Then use it:

            

              
              
my $gis = GIS::Distance->new('My::Formula');
my $km = $gis->distance( @coords );
            
          

The global $GIS::Distance::Formula::SELF is available when your _distance() subroutine is called if, and only if, the entry point was "distance" in GIS::Distance and NOT "distance_metal" in GIS::Distance or otherwise.

Much of the interface described in GIS::Distance is actually implemented by this module.

SUPPORT

See "SUPPORT" in GIS::Distance.

AUTHORS

See "AUTHORS" in GIS::Distance.

LICENSE

See "LICENSE" in GIS::Distance.