Loops: while and tail recursion support

afaik that feature isn't available in rules yet

a related request: #1269884: Inline rules support

tagging

something like that would be best added as separate rules plugin. I'm not sure though it's something we need in rules core.

ad #4:
How would this new feature improve ux?

well UX might be misleading here, maybe we'd like to name it developer experience, site builder experience. but anyways, USING rules implies that you are building / developing something :)

Indeed, still I think it's just a feature request. It's not making something simpler, it's extending functionality.

A foreach() is necessary to be able to loop over lists, what was an often requested feature in rules 1.x. Up to now a While() was not often requested and I'd consider its usage "advanced". Thus, it should be in a separate module.

However, if many folks come up and state their need for that + it comes with a decent UX, I'd be happy to include the feature. (What doesn't mean I'm going to work on it. Maybe, maybe not.)

I've encountered this use case and my solution was to turn the number into a list by creating what is essentially a casting action:

/**
 * Implements hook_rules_action_info()
 */
function moduleName_rules_action_info() {
  return array(
    'integer_to_list' => array(
      'label' => t('Turn integer into list'),
      'parameter' => array(
        'integer' => array('type' => 'integer', 'label' => t('Integer')),
      ),
      'provides' => array(
      	'converted_list' => array('type' => 'list<integer>', 'label' => t('Converted list')),
    	),
      'group' => t('moduleName'),      
    ),
  );
}

function integer_to_list($integer) {
	$new_list = array();
	for ($counter = 1; $counter <= $integer; $counter++) {
		$new_list[] = $counter;
	}
	
	return array('converted_list' => $new_list);
}

For Commerce quantity, you would have to change the input to a decimal.

* added shorter description and link to meta issue.
* opened #1525582: Action: generate a list from an integer to get #11 into rules core

my solution was... essentially a casting action

So, the patch in #1525582: Action: generate a list from an integer plus some docs would cover this feature?

If so, please change this to a docs issue or mark it as a duplicate, or move the other code here and mark that one as a duplicate.

NO.
there are while loops that can NOT be simulated with counter arrays.

for a classification see my meta issue #1525596: [Meta] Rules loops extended
where i elaborated now:

Comparison:
While-loops (which are guarded by some explicit condition) and tail recursion (which are guarded by a rules condition) are equivalent in expression strength.
Counter arrays are weaker, as the number of loops is calculated in advance. So they may cover many, but not all use cases.
I think we still need counter arrays because essentially a for-loop is often more readable than a while loop.

Let's first do counter array loops in #1525582: Action: generate a list from an integer, then come back to this. And, let's keep tail recursion separate in: #1525588: Looping: add recursion or tail recursion.

@axel.rutz: I think I might be confusing for and foreach, but one of them is what we already have, and the other is what we could do with #1525582: Action: generate a list from an integer and a "count a list" action. The while will be something else to be developed here. Could you please sort this out more clearly?

Is there any way we could just allow the user to specify the recursion limit? I think this would be a quick and entirely valid fix, and it would allow the user to tune rules to the particular application (i.e., a recursive limit of 2 might be a total joke for some people, whereas a recursion limit of 4 may be overkill for others). I feel the lack of such an option is really hurting the usability of rules.

#15: Sorting through these (tagged) issues has helped me understand the different methods, so nm the question.

Foreach is handled in #1525582: Action: generate a list from an integer, and #1525588: Looping: add recursion or tail recursion will require the same change as this issue to extend the recursion handler. I marked the tail recursion issue as a duplicate.

added short description

We're not going to be adding this feature into D7 Rules this late in the D7 lifecycle. New features should go into the 8.x-3.x branch first, and then be backported if there is interest from the community and participation by the community.

Postponed, because the maintainers won't be working on this. As stated above, the best way to get this into Rules is to implement it in an add-on module, then if there is demonstrated need we can consider this for core Rules.