Making all Traversables an Iterator or IteratorAggregate

Hi internals, Userland classes that implement Traversable must do so either through Iterator or IteratorAggregate. The same requirement does not exist for internal classes: They can implement the internal get_iterator mechanism, without exposing either the Iterator or IteratorAggregate APIs. This makes them usable in get_iterator(), but incompatible with any Iterator based APIs. A lot of internal classes do this, because exposing the userland APIs is simply a lot of work. I would like to add a general mechanism to make this simpler: https://github.com/php/php-src/pull/5216 adds a generic "InternalIterator" class, that essentially converts the internal get_iterator interface into a proper Iterator. Internal classes then only need to a) implement the IteratorAggregate interface and b) add a getIterator() method with an implementation looking like this: // WeakMap::getIterator(): Iterator ZEND_METHOD(WeakMap, getIterator) { if (zend_parse_parameters_none() == FAILURE) { return; } zend_create_internal_iterator_zval(return_value, ZEND_THIS); } This allows internal classes to trivially implement IteratorAggregate, and as such allows us to enforce that all Traversables implement Iterator or IteratorAggregate. Regards, Nikita