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Date: Mon, 30 Mar 2026 01:51:16 +0300
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Subject: Re: [PHP-DEV] RFC proposal: Invokable interface
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From: sandfox@sandfox.me (Anton Smirnov)

Hi!

On 30/03/2026 00:42, Osama Aldemeery wrote:
> It follows the Stringable pattern: auto-implemented for any class 
> defining __invoke(), explicitly implementable with enforcement, and 
> covariant to callable in return type checks.

Stringable is just a normal interface that can be used directly as any 
other regular interface, it's just also applied magically.

Invokable cannot be a regular interface because the signature for 
__invoke is not fixed, so it's a "weird" interface with magic behavior 
like Throwable and Iterable. What is common about these weird interfaces 
is that they can't be directly implemented by user. I don't feel like 
breaking this rule is a good idea for something with no clear benefits.

Second thing is that magic methods are not supposed to be used directly, 
so having __invoke is just an implementation detail, the consumer code 
should not check for that, that's a code smell.

Anton