Data::ConveyorBelt
my @data = ( 1 .. 15 );
my $machine = Data::ConveyorBelt->new;
$machine->getter( sub {
my( $limit, $offset ) = @_;
$offset ||= 0;
return [ @data[ $offset .. $offset + $limit ] ];
} );
$machine->add_filter( sub {
my( $data ) = @_;
return [ grep { $_ % 2 == 1 } @$data ];
} );
my $data = $machine->fetch( limit => 5 );
Returns a new Data::ConveyorBelt instance.
Gets/sets the getter subroutine \&getter that represents the list of items in your data source. Required before calling fetch.
A getter subroutine will be passed two arguments: the number of items to return, and the offset into the list (0-based). It must return a reference to the matching list of items.
Adds a filter subroutine \&filter to your chain of filters.
A filter will be passed a reference to a list of items as returned either from your getter or from a previous filter in the chain. A filter must return a reference to a list of items.
A filter can alter the size of the list of items, either removing or expanding items in the list. It can also transform the items in the list.
Fetches a list of items from your data source, passes them through your filters, and returns a reference to a list of items.
You must install a getter before calling fetch, but you don't have to install any filters. Running fetch without any filters does what you'd expect: it returns the values directly from your data source, unmodified and unfiltered.
%param can contain:
The number of items to return. Required.
The offset into the full list of items (0-based). Optional; defaults to 0.
The number of items to request at a time from your getter function.
For example, if your getter has high latency (reading from a network resource, for example), and if you suspect that your filters will be fairly aggressive--and will end up removing a good percentage of the items returned from the getter--you may want to fetch larger chunks of data at a time.
Optional; defaults to the same value as limit.
Data::ConveyorBelt is free software; you may redistribute it and/or modify it under the same terms as Perl itself.
Except where otherwise noted, Data::ConveyorBelt is Copyright 2007 Six Apart, cpan@sixapart.com.
