When a form element doesn't specify a #weight, it is assumed internally as #weight 0. However, to ensure that our form elements display visually *as they were defined in the array* we, in form_builder, count the number of elements, divide by 1000, and set that as the weight:
# Assign a decimal placeholder weight to preserve original array order
if (!isset($form[$key]['#weight'])) {
$form[$key]['#weight'] = $count/1000;
}
The above code will set the #weights of elements that have not defined a weight to something like 0 (first element in array definition), 0.001, 0.002, and so on. However, anytime a form element *explicitly* defines a #weight of 0, that #weight is kept at exactly 0, which would cause that form element to appear BEFORE the elements that didn't have a #weight defined (and thus received a #weight such as 0.002).
Consider the following pseudo example:
$form['game_title'] = array(
'#type' => 'textfield',
...
);
$form['game_description'] = array(
'#type' => 'textarea',
...
);
$form['game_format'] = filter_form(variable_get('game_format', NULL));
return $form;
Here, we're not definiing weights on our two textfields. We then add an filter_form. The second parameter of the filter_form is $weight, which defaults to 0. After this $form hits form_builder, we have weights 0 (game_title), 0.001 (game_description), and 0 (filter_form) respectively. This is then sorted by weight, which causes filter_form (the third element in the array) to appear BEFORE game_description (0 is lighter than 0.001).
The short lesson is: explicitly defining #weight 0 for a form element is probably a bad idea. This patch changes the default #weight of filter_form to NULL, instead of 0, and also removes any other explicit setting of #weight to 0 in core.
TODO:
+ The contact.module was broken; a new patch for contact.module is needed.
+ Documentation is needed.
+ The most important modules need to be updated ASAP.
All node revisions were stored in a serialized field in the node table and retrieved for _each_ page view although they are rarely needed. We created a separate revisions table which would be in principle identical to the node table, only that it could have several old copies of the same node. This also allows us to revision-related information, and to provide log entries to non-book pages when a new revision is being created.
TODO:
1. Provide upgrade instructions for node module maintainers!
2. Upgrade modules that implement node types.
3. Provide an upgarde path for revisions. Dependency on the upgrade system.
Gerhard Killesreiter
Dries Buytaert
Steven Wittens