On Thu, Jan 25, 2018 at 9:52 AM, Derick Rethans <der...@php.net> wrote:
> On Wed, 24 Jan 2018, Michael Morris wrote: > > > Ok, here's another idea I've been mulling over. This I know is possible > > because I've done it using user land code, specifically Drupal 8's > > Assertion\Inspector class. > > > > https://api.drupal.org/api/drupal/core%21lib%21Drupal%21Comp > onent%21Assertion%21Inspector.php/class/Inspector/8.5.x > > > > These methods provide a means to inspect collections - arrays usually but > > also Traversables. They fill a hole in the PHP library - the ability to > > check collection integrity. > > IMO, it makes a lot more sense to check integrity when creating the > "array" structure. Instead, I would suggest to add a native Collection > type, that takes a "type" as argument. They aren't quite full generics, > but it does 1. fix something; 2. isn't really complicated. > > What I am suggesting is to add a new syntax "Collection<$type>", > mimicking a class, but having a type as "argument": > > $a = new Collection<integer>; > > And then $a can act as if you'd use an ArrayAccess'ed class. > Upon each set or update, the type of the value can then be checked > against the type. > Agreed, and we can get *almost* there today with: $collection = collection_of('is_int', [ 1, 2 ]); $collection[] = M_PI; // exception thrown given: function collection_of(callable $validator, $input = []) { $collection = new class($input) extends \ArrayObject { public function offsetSet($index, $value) { if (($this->validator)($value)) return parent::offsetSet($index, $value); throw new \DomainException; } }; $collection->validator = $validator; foreach ($input as $key => $value) $collection[$key] = $value; return $collection; } > Consequently, this would also mean you can type hint on Collection<type> > instead of for example an earlier suggested array of type, where upon > passing in the array each member was checked for its type (slow). > Regrettably, class_alias cannot quite work here, because the validator is passed at run-time, so making this part of the language seems a good place to go. Cheers, bishop
