NAME
Data::ConveyorBelt
SYNOPSIS
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 );
DESCRIPTION
USAGE
Data::ConveyorBelt->new
Returns a new *Data::ConveyorBelt* instance.
$machine->getter( [ \&getter ] )
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.
$machine->add_filter( \&filter )
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.
$machine->fetch( %param )
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:
* limit
The number of items to return. Required.
* offset
The offset into the full list of items (0-based). Optional; defaults
to 0.
* chunk_size
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*.
LICENSE
*Data::ConveyorBelt* is free software; you may redistribute it and/or
modify it under the same terms as Perl itself.
AUTHOR & COPYRIGHT
Except where otherwise noted, *Data::ConveyorBelt* is Copyright 2007 Six
Apart,
[email protected].
