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Date: Thu, 9 Jan 2020 16:30:08 -0500
Cc: Ralph Schindler <ralph@ralphschindler.com>,
 Internals <internals@lists.php.net>
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To: Kalle Sommer Nielsen <kalle@php.net>
Subject: Re: [PHP-DEV] [RFC] Allow ::class on objects
From: mike@newclarity.net (Mike Schinkel)

> Den tor. 9. jan. 2020 kl. 22.41 skrev Mike Schinkel =
<mike@newclarity.net>:
>=20
> Traits are compiler assisted code copy/paste and not contracts (unlike
> interfaces), so there is no gain in having ::trait.

It can already be referring to using ::class so it makes little sense to =
disallow ::trait unless there is a different reason not to add another =
::keyword.

Traits are symbols, so it is not unreasonable that there would be a way =
to access it symbolically so that the reference can be type checked.

One of my use-cases for referring to traits is to provide helpful hints =
in error messages, i.e.:=20

printf( '%s does not implement %s. You can easily implement that =
interface by using %s',
	get_class( $this ),
	Interfaces\Foo::interface,
	Traits\Foo::trait,
);

>> use Interfaces;
>> if ( implements_interface( $object, =
Interfaces\MyInterface::interface, $trigger_error =3D 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:

But the instanceof operator does not fulfill my requirements.  I manage =
error triggering during development and logging during production within =
the function. Thus I can just use the implements_interface() function to =
handle errors automatically when I am testing an assertion vs. using it =
just for branching.

You'll note I explicitly included a third parameter `$trigger_error =3D =
true` in hopes people would notice, realize what I was doing and not =
think that I needed to be educated on the existence of instanceof.=20

-Mike=