Laravel - use dynamic parameter type in a method

I have following method inside Controller:

/**
     * Show the form for creating a new resource.
     * @param SkillForm|null $model
     * @return Renderable
     */
    public function form(?SkillForm $model): Renderable
    {
        return view('components.forms.index', [
            'model' => $model,
        ]);
    }

Is it possible for a type (SkillForm) to be set somewhere else as a static variable, and use that? For example (this doesn't work):

/**
         * Show the form for creating a new resource.
         * @param SkillForm|null $model
         * @return Renderable
         */
        public function form(?self::model $model): Renderable
        {
            return view('components.forms.index', [
                'model' => $model,
            ]);
        }

Dynamically defining the type of a method is not supported by PHP at the moment.

If your goal is to validate that it is the right type, there are a few options available

1. Use a common interface

   <?php
   
   interface A {}
   
   class B implements A {}
   class C implements A {}
   
   function foo(A $a) {}
   

   You could also use a Base class instead of interface, but usually interface
   is the preferred method.

2. Use type union

   <?php
   
   function foo(A|B $a) {}
   

3. Perform the check inside the function

   <?php
   
   class A
   {
       public static $model = 'SomeClass';
   
       public function foo($a)
       {
           throw_unless($a instanceof self::$model, Exception::class, "a is not an instance of " . self::$model);
       }
   }
   

The interface and union-type checks are usually better for IDE support and static analysis

>Short answer is PHP does not support dynamic typing for method parameters at runtime.

You can remove the type hint from the method signature and check the object type inside your method.

/**
 * Show the form for creating a new resource.
 *
 * @param mixed $model
 * @return Renderable
 */
public function form($model): Renderable
{
    if ($model instanceof SkillForm) {
        // handle SkillForm
    } elseif ($model instanceof AnotherForm) {
        // handle AnotherForm
    }
    
    return view('components.forms.index', [
        'model' => $model,
    ]);
}