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php - How to type hint the `$this` property in a trait

I have a trait that that is being used in a class. In that trait, I'd like to be able to type hint which class it is being used.

This trait would most likely be used by that one class only. I only separated its concerns for organization purposes.

class Foo extends Model
{
    use Concerns/HasBar;
}

trait HasBar
{
    public function bar()
    {
        $this->... // Type hint $this to Foo
    }
}

Undefined asked

2022-02-9

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Undefined answered · Answer 1 · 2022-02-9

You can use var tag inside yourHasBar::bar() method to type hint public members of the class

trait HasBar
{
    public function bar()
    {
        /* @var Foo $this */
        $this->... // Type hint $this to Foo
    }
}

Undefined answered · Answer 2 · 2022-02-9

There is no way you can put a restriction on a trait to be used exclusively within a specific class.

If you want to implement in such way you may create a sub class instead of using a trait.