Events vs Actions in UI Code

Created 2008-01-02 / Edited 2008-11-29

Happy New Year!

I've been grappling with a concept for a long time now (years), and thought I'd put it down here to cast about for insight.

Here is one way to handle UI events:

$page->add_action(add_new => 'Add New Entry');
$page->display; # displays template, waits for input
$action = $page->get_action;
if($action eq 'add_new') {

Here is another:

$page->add_action('Add New Entry' => sub {
$page->display; # displays template, waits for input, runs callbacks

The first is quite imperative. Show the page. Give me the result. Examine the result. Act. The second is much more declarative. I declare that were such an action to occur, this is what you should execute.

The second is the way that Seaside handles things. I'm not quite sure why I'm reluctant to adopt this method... perhaps simply my lack of experience with this construct is to blame. I think it's some sort of voice in the back of my head that doesn't like it because it is a bit too much like desktop GUI callbacks. But why should that be a bad thing? It seems to work just fine for those applications.

I think I'm thinking about this too much.