On Fri, Feb 28, 2020 at 11:59 AM Nikita Popov <nikita....@gmail.com> wrote:
> Hi internals, > > I'm currently trying to make sure that all internal Traversable classes > implement either Iterator or IteratorAggregate. This is a hard requirement > for userland classes, but internal classes can get away with implementing > only the internal get_iterator() mechanism. ( > https://github.com/php/php-src/pull/5216) > > One problem I ran into along the way is the SimpleXMLIterator class. A > naive person might think that there is some sanity left in this world, and > the hierarchy for SXE/SXI looks like this: > > SimpleXMLElement implements IteratorAggregate > // where SimpleXMLElement::getIterator() returns: > SimpleXMLIterator implements Iterator > > Of course, they would be wrong. The actual hierarchy is this: > > SimpleXMLElement implements Traversable > SimpleXMLIterator extends SimpleXMLElement implements Iterator > > The fact that SimpleXMLIterator extends SimpleXMLElement leaves me in a > tough spot, because it means SimpleXMLElement cannot be an > IteratorAggregate -- that would mean that SimpleXMLIterator implements both > IteratorAggregate and Iterator, which is not permissible. > > It seems that it's also not possible to remove the "extends" without a > non-trivial backwards-compatibility break, because apparently writing > simplexml_load_string($str, 'SimpleXMLIterator') is a thing, which requires > SimpleXMLIterator to extend SimpleXMLElement (and possibly is the reason > why this was done in the first place.) > > The only way out I see here is to lift the methods from SimpleXMLIterator > into SimpleXMLElement, make SimpleXMLElement implement Iterator itself, and > basically leave SimpleXMLIterator as a dummy extension of SimpleXMLElement. > > Does that sound "reasonable"? Or rather, is there something more > reasonable that can be done? > I've put up https://github.com/php/php-src/pull/5234 to implement this... Nikita
