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Date: Mon, 17 Jan 2022 13:03:52 -0500
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To: Rowan Tommins <rowan.collins@gmail.com>
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Subject: Re: [PHP-DEV] RFC: Trait expects interface
From: mike@newclarity.net (Mike Schinkel)

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> On Jan 7, 2022, at 1:56 PM, Rowan Tommins <rowan.collins@gmail.com> =
wrote:
>=20
> On 07/01/2022 13:47, Robert Korulczyk wrote:
>> I'm not really sure why would you not want this - what is the point =
of marking method as interface implementation, if it is not reflected by =
type system in actual execution?
>=20
>=20
> It's really quite simple: I don't want traits to tell me how I "must" =
use them, but am quite happy for them to document how I "can" use them.

About any of these someone could say "I don't want to be told..."=20

"...I must implement an abstract method"
"...I must implement all the methods in an interface"
"...I must pass all arguments declared in a function"
"...I must pass arguments that are of the type that were type-hinted"
"...I cannot extend a final class"
"...I cannot access a private property outside the class"
"...I cannot change a readonly property after it has been initialized"

And yet specifying appropriate constraints for a specific use-case has =
its benefits.  I'm sure you can see benefit to the above constraints so =
it is strange to me you cannot see the benefit of traits that would =
constrain their uses to requiring an interface.

If it were possible to specify that a trait required an interface then I =
don't envision anyone other than those who need bespoke traits would do =
so, and those are not likely traits you would want to use anyway because =
they could be changed by the developer when their use-case evolved.

#jmtcw #fwiw

-Mike

>=20
> Unless we allow a trait to *automatically* implement the interface (or =
similar features, such as an interface with default implementation) =
there is no direct impact on the actual type system. There are, as far =
as I can see, three things the feature would provide:
>=20
> - Documentation: the trait can tell me as a programmer that it =
contains everything I need to implement a particular interface
> - Code generation: the trait can import the list of methods from an =
interface as abstract methods which it requires
> - Policing: the trait can force me as a programmer to use it in a =
certain way; this is the part I don't see the need for
>=20
> Regards,
>=20
> --=20
> Rowan Tommins
> [IMSoP]
>=20
> --=20
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: https://www.php.net/unsub.php
>=20


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