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Date: Thu, 9 Jan 2020 23:02:31 +0200
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To: Mike Schinkel <mike@newclarity.net>
Cc: Ralph Schindler <ralph@ralphschindler.com>, Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Allow ::class on objects
From: kalle@php.net (Kalle Sommer Nielsen)

Moi

Den tor. 9. jan. 2020 kl. 22.41 skrev Mike Schinkel <mike@newclarity.net>:
>
> > On Jan 9, 2020, at 3:29 PM, Ralph Schindler <ralph@ralphschindler.com> wrote:How would you get the right semantics out of $object::interface, or $object::trait, and/or do you have an example of what you're expecting?
>
> Sorry, I was only thinking about using it on Interface and Trait names, not on objects.

Traits are compiler assisted code copy/paste and not contracts (unlike
interfaces), so there is no gain in having ::trait.

> I have a lot of code that looks like this:
>
> use Interfaces;
> if ( ! implements_interface( $object, Interfaces\MyInterface::class, $trigger_error = true )) {
>    return;
> }
>
> And it feels wrong. I would love to be able to use ::interface, i.e.:
>
> use Interfaces;
> if ( implements_interface( $object, Interfaces\MyInterface::interface, $trigger_error = true )) {
>    return;
> }

If your $object variable is an actual instance, you can use the
instanceof operator, it treats the right operand as a first class
citizen and allows you to skip writing ::class:

use Interfaces;
if(!$object instanceof Interfaces\MyInterface)
{
// Notice the ! is right associative and instanceof is non
associative, hence the lack of parantheses
}

use Interfaces;
if($object instanceof Interfaces\MyInterface)
{
}

-- 
regards,

Kalle Sommer Nielsen
kalle@php.net