Views handlers on "Configure views" page are hard-coded

Think I figured out the fix: Seems the default handlers are hard-corded into the data_get_views_handler_options function of data.views.inc:

function data_get_views_handler_options($type = NULL, $reset = FALSE) {
  static $handlers;
  if (!isset($handlers) || $reset) {
    $handlers = array();
    $handlers['field'] = array(
      'views_handler_field' => 'views_handler_field',
      'views_handler_field_numeric' => 'views_handler_field_numeric',
      'views_handler_field_date' => 'views_handler_field_date',
      'views_handler_field_url' => 'views_handler_field_url',
      'views_handler_field_data_markup' => 'views_handler_field_data_markup',
    );
    $handlers['filter'] = array(
      'views_handler_filter_date' => 'views_handler_filter_date',
      'views_handler_filter_float' => 'views_handler_filter_float',
      'views_handler_filter_numeric' => 'views_handler_filter_numeric',
      'views_handler_filter_string' => 'views_handler_filter_string',
    );
    $handlers['argument'] = array(
      'views_handler_argument' => 'views_handler_argument',
      'views_handler_argument_date' => 'views_handler_argument_date',
      'views_handler_argument_numeric' => 'views_handler_argument_numeric',
      'views_handler_argument_string' => 'views_handler_argument_string',
    );
    $handlers['sort'] = array(
      'views_handler_sort' => 'views_handler_sort',
      'views_handler_sort_date' => 'views_handler_sort_date',
    );
    // Allow other modules to alter the list of available handlers.
    drupal_alter('data_views_handlers', $handlers);
  }
  return isset($type) && isset($handlers[$type]) ? $handlers[$type] : $handlers;
}

Any reason why views_discover_handlers can't be used to populate the dropdown selections?
http://api.zzolo.org/api/function/views_discover_handlers/drupal-6

It returns a lump-sum array of all handlers available, but if I understand correctly, all filter/sort/field/argument handlers have their type as part of the machine-code name, right? Shouldn't be hard to list them correctly, right?

Anyone have thoughts?

Oh, and apparently that discover function isn't going to be around for D7, but I wasn't sure what would replace it, so I started this issue:
#950020: How to get an array of all handlers

Alright, so I just realized that this still doesn't solve my date api handler issue (because date_api_filter_handle isn't discovered by views_discover_handlers), but this still gives more handler options, so I can't see why it wouldn't be included (unless my code is too sloppy?)

function data_get_views_handler_options($type = NULL, $reset = FALSE) {
  static $handlers;
  if (!isset($handlers) || $reset) {
    $handlers = array();
    module_load_include('inc', 'views', 'includes/base');
    module_load_include('inc', 'views', 'includes/handlers');
    $available_handlers = views_discover_handlers();
    $handlers = array(
      'field',
      'filter',
      'argument',
      'sort',
    );
    foreach ($available_handlers as $available_handler => $def) {
      foreach($handlers as $handler) {
        $pattern = '/^views_handler_';
        $pattern .= $handler;
        $pattern .= '([_][^_.]+)*$/';
        if (preg_match($pattern, $available_handler)) {
          $handlers[$handler][$available_handler] = $available_handler;
        };
      };
    };
    // Allow other modules to alter the list of available handlers.
    drupal_alter('data_views_handlers', $handlers);
  }
  return isset($type) && isset($handlers[$type]) ? $handlers[$type] : $handlers;
}

Mhen... drupal_alter it is. I figured there must've been a way to find all handlers automatically, but this isn't worth the effort.

Anyone willing to review what I have above anyhow? I think it's still a step above what's there now.

Alright, so technically, it seems that views_discover_handlers() should find any handler that's been registered with hook_views_handlers(), and date_api_views_handlers() was declared in date_api.views.inc.

But for some reason it's only returning the core handlers... any thoughts?

Alright, so maybe this is going to explode d.o, but here goes: MY. VERY. FIRST. PATCH.

Spent a few days figuring out git and getting it going, so hopefully this works. Let me know if it's in the wrong format or something.

Cheers.

Sorry, used git format-patch instead of git diff.