NAME

Adapter::Async - provides a way to link a data source with a view

VERSION

Version 0.001

DESCRIPTION

Accessing data

• count - resolves with the number of items. If this isn't possible, an estimate may be acceptable.

   say "items: " . $adapter->count->get

• get - accepts a list of indices

   $adapter->get(
    items   => [1,2,3],
    on_item => sub { ... }
   )->on_done(sub { warn "all done, full list of items: @{$_[0]}" })

  The returned list of items are guaranteed not to be modified further, if you want to store the arrayref directly.

This means we have double-notify on get: a request for (1,2,3,4) needs to fire events for each of 1,2,3,4, and also return the list of all of them on completion (by resolving a Future).

Modification

• clear - remove all data

• splice - modify by adding/removing items at a given point

Helper methods provide the following:

• insert - splice $idx, @data, 0

• append - splice $idx + 1, @data, 0

Events

All events are shared over a common bus for each data source, in the usual fashion - adapters and views can subscribe to the ones they're interested in, and publish events at any time.

The adapter raises these:

• item_changed - the given item has been modified. by default only applies to elements that were marked as visible.

• splice - changes to the array which remove or add elements

• move - an existing element moves to a new position (some adapters may not be able to differentiate between this and splice: if in doubt, use splice instead, don't report as a move unless it's guaranteed to be existing items)

   index, length, offset (+/-)

The view raises these:

• visible - indicates visibility of one or more items. change events will start being sent for these items.

   visible => [1,2,3,4,5,6]

  Filters may result in a list with gaps:

   visible => [1,3,4,8,9,10]

  Note that "visible" means "the user is able to see this data", so they'd be a single page of data rather than the entire set when no filters are applied. Visibility changes often - scrolling will trigger a visible/hidden pair for example.

  Also note that ->get may be called on any element, regardless of visibility - prefetching is one common example here.

• hidden - no longer visible.

   hidden => [1,2,4]

• selected - this item is now part of an active selection. could be used to block deletes.

   selected => [1,4,5,6]

• highlight - mouse over, cursor, etc.

   highlight => 1

  Some views won't raise this - if touch control is involved, for example

• activate - some action has been performed.

   activate => [1]
   activate => [1,2,5,6,7,8]

  Multi-activate will typically happen when items have been selected rather than just highlighted.

  The adapter itself doesn't do much with this.

AUTHOR

Tom Molesworth <cpan@perlsite.co.uk>

LICENSE

Copyright Tom Molesworth 2013-2014. Licensed under the same terms as Perl itself.