Checking that Closure is static

18 june 2021 at 17:35, Dmitry Eliseev elisdnru@gmail.com:

Hello! When I use a static anonymous function as an HTTP-action in some frameworks like:

$app = new App();
$app->get('/', static function () {
return new Response('Hello!);
})

I get a warning "Cannot bind an instance to a static closure" in every $closure->bind($container) call inside of the framework.

But right now I cannot prevent this warning because there is no native way to check that closure is static before calling the bind method. I can only suppress the warning with @ or set/restore_error_handler pair.

So I propose to add a method like Closure::isStatic for ability of manual checking it before bind call:

if (!$closure->isStatic()) {
$closure->bind($object);
}

The method can contain simple statement:

return func->common.fn_flags & ZEND_ACC_STATIC;

It will be helpful if somebody needs to support dynamic and static callables both without warnings.

I sent Pull Request https://github.com/php/php-src/pull/7193 with a
simple implementation.

P.S. Sorry for PR without RFC, but I have not got any reply to my proposal yet.

Le 18 juin 2021 à 16:35, Дмитрий Елисеев elisdnru@gmail.com a écrit :

Hello! When I use a static anonymous function as an HTTP-action in
some frameworks like:

$app = new App();
$app->get('/', static function () {
return new Response('Hello!);
})

I get a warning "Cannot bind an instance to a static closure" in every
$closure->bind($container) call inside of the framework.

But right now I cannot prevent this warning because there is no native
way to check that closure is static before calling the bind method. I
can only suppress the warning with @ or set/restore_error_handler
pair.

So I propose to add a method like Closure::isStatic (or
Closure::canBeBound, etc.) for ability of manual checking it before
bind call:

if (!$closure->isStatic()) {
$closure->bind($object);
}

The method can contain simple statement:

return func->common.fn_flags & ZEND_ACC_STATIC;

It will be helpful if somebody needs to support dynamic and static
callables both without warnings.

-- Best, Dmitry

I think that the Warning should be removed entirely, and the bindTo() method should be a no-op when applied to a static closure.

That the closure is implemented as static, or as non-static without actually using $this, is an implementation detail that the user of the closure doesn’t need to be aware.

As a precedent, it is perfectly legal to call a static class method on an instance of that class: https://3v4l.org/5QKsN https://3v4l.org/5QKsN

—Claude