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Ok, so maybe this is old hat, but I found it incredible
simple to implement and even understand. So here’s the scenario... I have an object which
contains all the attributes of a reservation. I also have a list class which
contains many of my reservation objects. What I want is a count of how many of
each type of room I would need if all these reservations were to be submitted
for creation so I can reject them all up front before going through the effort
of running out of inventory half way through creating them. In SQL, it would be easy: SELECT room_type, Count(*) FROM reservations_to_be GROUP BY room_type Here’s what I did given my existing structures: my %RoomTypes; $self->get_list->rewind; while (my $o_rl =
$self->get_list->next) { $RoomTypes{$o_rl->get_room_type}++; } So now, I can pre-check availability based on summary
counts: If ($RoomTypes{“KN”} > [_some
other availability number_]) { die “Not
enough inventory available to fulfill request”; } The cool part about this is the key won’t exist unless
there is at least one room type being requested in my batch or requests –
it gets added automagically as it’s found. Plus, if I want to further
break it down Say, counts per type per day), I can just add more keys when
adding it up: my %RoomTypes; $self->get_list->rewind; while (my $o_rl =
$self->get_list->next) { my $StartDate; my $EndDate =
$o_rl->get_depart_date('obj'); for ($StartDate =
$o_rl->get_arrival_date('obj'); $StartDate <= $EndDate; $StartDate +=
"1D" ) {
$RoomTypes{$StartDate->format("%Y-%m-%d")}{$o_rl->get_room_type}++; } } If ($RoomTypes{“2005-10-01”}{“KN”}
> [_some other availability number_]) { die “Not
enough inventory available to fulfill request”; } |