1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
|
package GIS::Distance::Formula;
use 5.008001;
use strictures 2;
our $VERSION = '0.20';
use Class::Measure::Length qw( length );
use Carp qw( croak );
use Scalar::Util qw( blessed );
use namespace::clean;
our $SELF;
sub new {
my $class = shift;
my $args = $class->BUILDARGS( @_ );
my $self = bless { %$args }, $class;
$self->{code} = $class->can('_distance');
$self->BUILD() if $self->can('BUILD');
return $self;
}
sub BUILDARGS {
my $class = shift;
return shift
if @_==1 and ref($_[0]) eq 'HASH';
return { @_ };
}
sub distance {
my $self = shift;
my @coords;
foreach my $coord (@_) {
if ((blessed($coord)||'') eq 'Geo::Point') {
push @coords, $coord->latlong();
next;
}
push @coords, $coord;
}
croak 'Invalid arguments passsed to distance()'
if @coords!=4;
local $SELF = $self;
return length(
$self->{code}->( @coords ),
'km',
);
}
sub distance_metal {
my $self = shift;
return $self->{code}->( @_ );
}
1;
__END__
=encoding utf8
=head1 NAME
GIS::Distance::Formula - Formula base class.
=head1 DESCRIPTION
This is the parent class for all L<GIS::Distance> formula classes such as
those listed at L<GIS::Distance/FORMULAS>.
To author your own formula class:
package My::Formula;
use parent 'GIS::Distance::Formula';
sub _distance {
my ($lat1, $lon1, $lat2, $lon2) = @_;
# ...
return $kilometers;
}
1;
Then use it:
my $gis = GIS::Distance->new('My::Formula');
my $km = $gis->distance( @coords );
The global C<$GIS::Distance::Formula::SELF> is available when your
C<_distance()> subroutine is called if, and only if, the entry point
was L<GIS::Distance/distance> and NOT L<GIS::Distance/distance_metal>
or otherwise.
Much of the interface described in L<GIS::Distance> is actually
implemented by this module.
=head1 SUPPORT
See L<GIS::Distance/SUPPORT>.
=head1 AUTHORS
See L<GIS::Distance/AUTHORS>.
=head1 LICENSE
See L<GIS::Distance/LICENSE>.
=cut
|
