Provide hooks for modules to provide special identifiers for custom breadcrumbs, capable of building multiple crumbs

Unfortunately the attached patch files disapperead, so have to upload it again.

Attached the same patch, but without trailing spaces diffs, so it should be more readable.

Also needs http://drupal.org/files/issues/custom_breadcrumbs.identifiers.inc__0.txt from above

New patch attached, because I did not call custom_breadcrumbs_get_identifiers() in theme_custom_breadcrumbs_help_identifiers().

http://drupal.org/files/issues/custom_breadcrumbs.identifiers.inc__0.txt still required.

Thanks for your quick answer.
I don't understand what you mean with "approch in tokenSTARTER", or better to say, I cannot see a differenece to the current patch's approach. So maybe you could explain your thoughts to me.

As you said it would be nice to have a custom_breadcrumbs_identifiers.module that contains some basic identifiers. I agree, but the main functionality (hook implementation, _custom_breadcrumbs_create_crumb_items()) has to stay in custom_breadcrumbs core. What can be done is to move custom_breadcrumbs.identifiers.inc and custom_breadcrumbscb_identifiers_info() to the submodule (custom_breadcrumbs_identifiers.module).

One thing I don't like about my patch is the handling of $locations for menu set active trail. dereine suggested to use a ctools plugin to remove $locations from the functions. At the moment I don't exactly know, how it could be done with ctools, but could be worth a try.

I'm looking forward to review the patch. But cannot promise to do it until the weekend.

MGN, couldn't review it, but will do it tomorrow. Just wrote it down to my todo-list ...

I finally found time to review your patch.

With your implementation in _custom_breadcrumbs_create_crumb_items() on line 535 you built in a "new feature". As I'm not sure you recognized it, I'll point it out:
Modules can implement identifiers in hook_cb_identifiers_values() without defining them in hook_cb_identifiers_list().
This is an advantage for building multiidentifiers ([identifier-*]) or identifiers with options [identifier:bold:12px]. On the other hand it does not check if the module is "owner" of the identifier by identifying it in hook_cb_identifiers_list(). This is no problem, it only confused me in the first moment.

return value check in _custom_breadcrumbs_create_crumb_items()

A Problem is your return value check in line 537. There the return should be checked on NULL, because a value-function may implement an empty array ( return array()), so it can define an item, that does not return any crumb items. For example this is necessary for a parent-menu-item implementation - if there is no parent item, there should be no crumb for that.

In the attached patch I replaced line 537 with

    // Break on the first implementation that does return a value not NULL.
    if (isset($values)) break;

line 539 with if (isset($values)) {.
In custom_breadcrumbs_identifiers_cb_identifier_values there should be set line 45 to $crumb_items = NULL;.

I built a module to implement a parent-menu identifier. It's located on http://github.com/derhasi/dev/tree/custom_breadcrumbs_identifier.

enable custom_breadcrumbs_identifiers on update

For legacy reasons, the new submodule should be enabled automatically, to avoid missing identifiers:
therefore I adjusted custom_breadcrumbs.install:

/**
 * Enable custom_breadcrumbs_identifiers for legacy.
 */
function custom_breadcrumbs_update_6203() {
  module_enable(array('custom_breadcrumbs_identifiers'));
  $return[] = array(
    'success' => module_exists('custom_breadcrumbs_identifiers'),
    'query' => 'Custom_breadcrumbs_identifiers was enabled for legacy reasons. Please disable it, if you do not use special identifiers in your bredcrumb settings.',
  );
  return $return;
}

title check in _custom_breadcrumbs_get_trail_items()

as some identifiers do not need a title to be set, I'd remove or move the title check. Did not implement a "fix" for that in the attachment.

Besides I adjusted the custom_breadcrumbs_identifiers module to fit in coding standards.