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Date: Tue, 29 Mar 2022 13:34:01 +0100
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Subject: Re: [PHP-DEV] instance version of match ?
From: rowan.collins@gmail.com (Rowan Tommins)

On 29/03/2022 11:59, Robert Landers wrote:
>          $object instanceof AnotherInterface => 'bar',
>
> We can see that `SomeInterface` will resolve the interface and not the
> constant.


Yeah, the instanceof operator is magic in that regard - it has a special 
parsing rule to consume the next token and avoid it being evaluated as a 
constant.


> I think what they are proposing is that when the match is an object,
> and the branches are class/interface/etc names, it should just do an
> `instanceof` operation instead of a value-equals operation.


That wouldn't work, because the type of value passed to match() can vary 
at run-time, but you'd need to compile the expression one way or the other.

If it did work, it would be extremely confusing:

function example(string|object $input) {
     return match($input)  {
           SomeClass => 'found class',
          SOME_CONSTANT => 'found constant',
     };
}
var_dump( example(new SomeClass) );
var_dump( example(SOME_CONSTANT) );

Do both of those matches succeed? What if I set `const SomeClass = 
'hello';`?


So unfortunately we need some extra syntax to say that something should 
be an instanceof check, and therefore a class name.

Regards,

-- 
Rowan Tommins
[IMSoP]