Potential Union Types in PHP

_example.php

<?php

// Class version:

$tf = new ThingFinder()
$thing = $tf->find( new IntOrString( 123 ) )
// or 
$thing = $tf->find( new IntOrString( "foo" ) )
// or 
$thing = $tf->find( new IntOrString( true ) ) // Throws undefined thing error, or returns null.

// Versus "Union" version:

$tf = new ThingFinder()
$thing = $tf->find( 123 )
// or 
$thing = $tf->find( foo )
// or 
$thing = $tf->find( true ) // Throws "not an int or string" error.

IntOrString.class.php

<?php

class intOrString {
	public $value;

	function __construct( $value ) {
		$this->value = $value;
	}

	function toInt(): int {
		return (int)$this->value;
	}

	function toString(): string {
		return (string)$this->value;
	}

	function type(): string {
		return is_int( $this->value )
			? 'int'
			: 'string';
	}

}

IntOrString.union.php

union intOrString { 
   int
   string 
}

Thing.class.php

class Thing {

}

ThingFinder.class.php

class ThingFinder {

	function find( intOrString $id ): Thing {
		switch ( $id->type() ) {
			case 'int':
				$thing = $this->findByInt( $id->toInt() );
				break;
			default:
				$thing = $this->findByString( $id->toString() );
				break;
		}
		return $thing;
	}
	function altFind( intOrString $id ): Thing {
		if ( is_null( $thing = $this->findByInt( $id->toInt() ) ) ) {;
			$thing = $this->findByString( $id->toString() );
		}
		return $thing;
	}
	function findByInt( int $id ): Thing {
		return new Thing();
	}
	function findByString( string $id ): Thing {
		return new Thing();
	}
}