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Date: Wed, 25 Mar 2026 12:49:08 +0000
To: Robert Humphries <contact@developer-rob.co.uk>
Cc: internals@lists.php.net
Subject: Re: [PHP-DEV] [IDEA for RFC] class_uses and optionally returning traits for parent classes
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From: internals@gpb.moe ("Gina P. Banyard")

On Wednesday, 25 March 2026 at 07:40, Robert Humphries <contact@developer-r=
ob.co.uk> wrote:

> Good Morning Internals,
>=20
> I am aware that traits in general are a topic where people can have
> strong opinions, so I wanted to get an idea of initial thoughts on
> this before deciding if it is worth looking into any further.
>=20
> At the moment, there are three functions in SPL that allow access to
> what a given class is using in some way:
> * `class_implements`
> * `class_parents`
> * `class_uses` (returns the traits the current class uses)
>=20
> `class_uses` is unique out of the three in that it only returns traits
> declared on the current class as opposed to the parent class (and
> higher in inheritance). While this is documented in the manual,
> looking at the original bug ticket that introduced `class_uses`
> (https://bugs.php.net/bug.php?id=3D55266) then it isn't documented why
> it only returns traits on the current class. As far as I can tell from
> the bug ticket and the code, `class_implements` was copied for
> `class_uses` and while `_zend_class_entry->interaces` contains all
> interfaces (including from the parent classes),
> `_zend_class_entry->interaces->trait_names` does not.
>=20
> So, in terms of my question; what would be the general thoughts on a
> new optional argument to `class_uses` that iterates to each parent
> class, adding the traits from the parent as well?

Frankly I don't like the existence of these 3 functions in SPL.
This is very much in Reflection territory, and it should only ever be in Re=
flection.
SPL is already a mess of badly designed "features" trying to cohabitate.
The Reflection extension is designed to give you access to do introspection=
 with a well-defined API.


But more over I don't even think you addition makes that much sense.
Traits are not part of the inheritance hierarchy, that's because the "compo=
sition" of traits is effectively just copy and paste.
Interfaces are fully inherited onto any child class, so there is no need to=
 iterate through the parents to gather all interfaces.
Traits do not work this way, any "prior" use information is not transmitted=
 due to the copy and paste nature of them.
The current API doesn't even tell you if used traits also use other traits.
I don't even know how it handles trait aliases, or if it even cares about t=
hem.
And that's not even going through overridden trait methods/props/constants =
at any stage of the inheritance chain.

So I'm very much not convinced about this, nor do I see really the utility =
of wanting this information?
But anyway here is a small snippet that will fetch all used traits: https:/=
/3v4l.org/kvQGR


Best regards,

Gina P. Banyard