Change DateRange methods to attributes.

This means they will only be calculated once, and e.g. calling code
doesn't have to worry about caching them. Include documentation.

perllib/FixMyStreet/DateRange.pm

@@ -1,3 +1,16 @@
+=head1 NAME
+
+FixMyStreet::DateRange - little wrapper of an inclusive date range
+
+=head1 SYNOPSIS
+
+Given a start/end date, this can be used to return DBIx::Class parameters for
+searching within that date range, inclusive of both start and end dates.
+
+=head1 DESCRIPTION
+
+=cut
+
 package FixMyStreet::DateRange;
 
 use DateTime;
@@ -7,23 +20,38 @@ use Try::Tiny;
 
 my $one_day = DateTime::Duration->new( days => 1 );
 
+=over 4
+
+=item * start_date and end_date - provided start and end dates, to be parsed
+
+=cut
+
 has start_date => ( is => 'ro' );
 
+=item * start_default - default to use if start_date not provided
+
+=cut
+
 has start_default => ( is => 'ro' );
 
 has end_date => ( is => 'ro' );
 
+=item * parser - defaults to DateTime::Format::Flexible
+
+=cut
+
 has parser => (
     is => 'ro',
     default => sub { DateTime::Format::Flexible->new }
 );
 
+=item * formatter - defaults to same as parser
+
+=cut
+
 has formatter => (
     is => 'lazy',
-    default => sub {
-        my $self = shift;
-        return $self->parser;
-    }
+    default => sub { $_[0]->parser }
 );
 
 sub _dt {
@@ -36,37 +64,70 @@ sub _dt {
     return $d;
 }
 
-sub start {
-    my $self = shift;
-    $self->_dt($self->start_date) || $self->start_default
-}
+=back
 
-sub end {
-    my $self = shift;
-    my $d = $self->_dt($self->end_date);
-    $d += $one_day if $d;
-    return $d;
-}
+=head2 METHODS
+
+=over 4
+
+=item * start / end - provides DateTimes of the start/end of the range
+
+=cut
+
+has start => (
+    is => 'lazy',
+    default => sub {
+        $_[0]->_dt($_[0]->start_date) || $_[0]->start_default
+    }
+);
+
+has end => (
+    is => 'lazy',
+    default => sub {
+        my $d = $_[0]->_dt($_[0]->end_date);
+        $d += $one_day if $d;
+        return $d;
+    }
+);
 
 sub _formatted {
     my ($self, $dt) = @_;
     return unless $dt;
     $self->formatter->format_datetime($dt);
 }
 
-sub start_formatted { $_[0]->_formatted($_[0]->start) }
-sub end_formatted { $_[0]->_formatted($_[0]->end) }
+=item * start_formatted / end_formatted - formatted timestamps
 
-sub sql {
-    my ($self, $default) = @_;
-    my $sql = {};
-    if (my $start = $self->start_formatted) {
-        $sql->{'>='} = $start;
-    }
-    if (my $end = $self->end_formatted) {
-        $sql->{'<'} = $end;
+=cut
+
+has start_formatted => (
+    is => 'lazy',
+    default => sub { $_[0]->_formatted($_[0]->start) }
+);
+
+has end_formatted => (
+    is => 'lazy',
+    default => sub { $_[0]->_formatted($_[0]->end) }
+);
+
+=item * sql - returns a hashref of two comparison operators for the range
+
+=back
+
+=cut
+
+has sql => (
+    is => 'lazy',
+    default => sub {
+        my $sql = {};
+        if (my $start = $_[0]->start_formatted) {
+            $sql->{'>='} = $start;
+        }
+        if (my $end = $_[0]->end_formatted) {
+            $sql->{'<'} = $end;
+        }
+        return $sql;
     }
-    return $sql;
-}
+);
 
 1;