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Date: Fri, 29 Jan 2021 09:14:26 +0100
To: PHP Internals <internals@lists.php.net>
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Subject: [DISCUSSION] ReflectionType::accepts
From: brendt@stitcher.io (Brent Roose)

Hi Internals

Since the addition of union types, it has become a little more =
cumbersome to determine whether a given parameter type accepts specific =
input. Personally I've been reusing this code blob in several places =
because of it:

```
/** @var \ReflectionNamedType[] $types */
$types =3D match ($type::class) {
    ReflectionUnionType::class =3D> $type->getTypes(),
    ReflectionNamedType::class =3D> [$type],
};

foreach ($types as $type) {
    if (! is_subclass_of($type->getName(), ShouldBeStored::class)) {
        continue;
    }

    // =E2=80=A6
}
```

I wonder whether we would discuss adding a method on ReflectionType that =
accepts any given input, and tells you whether that input is valid for =
that type or not. I was thinking about =
`ReflectionType::accepts(string|object $input): bool` but we could =
discuss another name. With it, the above example could be refactored =
like so:

```
if (! $type->accepts(ShouldBeStored::class)) {
    return;
}

// =E2=80=A6
```

I believe this method should accept both class names and objects to be =
consistent with the existing reflection API. It would also work with =
intersection types, if they are to be added some day.

What do you think?

Kind regards
Brent