polymorphic string based checks

[exussum12]

I'm not sure if this is an error, as the code should check in a better way but I have come across the following

https://phpstan.org/r/051b7ab22cbb5241e32200e723a0bf3c

This should use instanceof ideally which resolves the issue, just wondering if code like this should also verify ?

Using something like

switch ($object->getType()) {
     case something::class :
}

vs

switch (true) {
     case $object instanceof something :
}

[ondrejmirtes]

Hi, can you express yourself more clearly? Looks like you’re talking about two different things (there’s no switch in the linked playground) but I’m not sure.

On Sat, 4 Aug 2018 at 13:28, Scott Dutton ***@***.***> wrote: I'm not sure if this is an error, as the code should check in a better way but I have come across the following https://phpstan.org/r/051b7ab22cbb5241e32200e723a0bf3c This should use instanceof ideally which resolves the issue, just wondering if code like this should also verify ? Using something like switch ($object->getType()) { case something::class : } vs switch (true) { case $object instanceof something : } — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#1330>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAGZuFmpIXQi_S2djqvolM_8GGQSM1mNks5uNYV0gaJpZM4Vu9fa> .

-- Ondřej Mirtes

[JanTvrdik]

I think that the idea is that when $obj->getType() return value of type static<$obj> then $obj->getType() === Foo::class should be resolved the same way as $obj instanceof Foo which would require understanding that static<$obj> depends on type of $obj.

[ondrejmirtes]

This might be doable with a custom type-specifying extension, you can find out about them in the README and there's plenty of examples in the codebase:

function test(contract $c) {
	if ($c->getType() === concrete::class) {
		concrete($c);	
	}
}

Supporting it in a switch statement is a completely different beast and it's not possible right now. Only these two forms are now supported in switch:

switch (true) {
    case $foo instanceof Foo:
}

And:

switch (get_class($foo)) {
    case Foo::class:
}

Waiting for confirmation from @exussum12 that this is solved so I can close this.

[exussum12]

Sorry, reading it back its not too clear

https://phpstan.org/r/25cbd9a4d5f1e16972e503079d3819b7

The result of the two loops are really identical, though the top loop checks by comparing strings and bottom loop checks by using instanceof.

Not sure if this should be a bug, as although its type safe - knowing that by comparing strings doesn't feel right.

This is only an issue with late static bindings.

Hopefully this example makes the issue more clear.

The code can 100% be improved here, its just as an example

[ondrejmirtes]

Yeah, PHPStan has no way of understanding the connection between $a->getType() string and $a type without a type-specifying extension. And it still won't work with switch statements because it wasn't thought of during implementation.

[exussum12]

ok so a custom type check would be fine if the switch was converted to a few ifs ?

[ondrejmirtes]

I'm now realizing that you can't write an extension for $a->getType === Foo::class because it's not a function/method. You'd have to rewrite your code to something like if (isType($a->getType(), Foo::class)), then it would work (you can write type-specifying extensions for functions, instance methods and static methods).

What are you implementing using the getType() method that you cannot use instanceof?

[exussum12]

Im not implementing this is in older code.

I have moved this for now to the switch (true) method, I just raised the bug report as technically the code was correct before also. Though I understand why it wouldnt be picked up as being right