Re: Re: [Concept] Magic Casting

On Fri, Dec 2, 2016 at 4:53 PM, Alex Bowers <bowersbros@gmail.com> wrote: > > On 2 December 2016 at 14:46, Andrey Andreev <narf@devilix.net> wrote: > >> A magic method is essentially an implicit interface ... >> The interface itself does nothing. But when it is implemented, the engine >> will know that the class constructor is public and accepts a single >> parameter - thus, also knowing that it could try to do a new >> ClassName($yourParameterHere) >> > > The interface would not work though, because there should be some logic in > place too. For example, if you accept, but convert an array, or an array of > arrays etc differently. Or would this be logic that should be placed inside > of the constructor, and the castable will just offload to a new > construction? > There's no logic in constructing differently from the same input type. If you handle an array passed to __cast() differently to one passed to __construct(), your design is inconsistent, to say the least. The only reason I can think of wanting to do that is if you'd like to magically create dependencies to pass to the constructor. For example: class Foo { public function __construct($scalar, Bar $bar) { // whatever } public static function __cast($var) { $bar = new Bar(); return new static($var, $bar); } } However, that is obviously tight-coupling at least one of your dependencies. I believe most people on the list would agree that this is not a good thing, but even if that wasn't the case - you could still do it in the constructor if you really wanted to: public function __construct($scalar, Bar $bar = null) { if ( ! isset($bar)) { $bar = new Bar(); } } Honestly, I don't see how a new method is in any way beneficial. Cheers, Andrey.