<?php

/**
 * @name Custom casting helper
 * @author [email protected]
 * @internal
 */
interface Castable {
    static function cast($var);
}

/**
 * @example hard casting (validation)
 */
class ValidatedPositiveInteger implements Castable {
    static function cast($var) {
        if(!is_int($var)) {
            throw new InvalidArgumentException('Value is not an integer');
        }
        if($var < 1) {
            throw new InvalidArgumentException('Integer is not positive');
        }
        return $var;
    }
}

/**
 * @example soft casting (sanitization)
 */
class SanitizedPositiveInteger implements Castable {
    static function cast($var) {
        $var = (int)$var;
        if($var < 1) $var = 1;
        return $var;
    }
}

// usage:

$var = (ClassName)$var;

function foo(ClassName $var) {}

// in both cases will run under the hood:

if($var instanceof Castable) $var = ClassName::cast($var);
else { /*current behavior*/ }

// usable cases:

// 1. custom types with internal logic
// 2. sanitization and validation of input
// 3. casting from array to object (e.g. json, db row, etc.)
// 4. casting from stdClass to object
// 5. custom type juggling
// 6. custom context dependent serialization/unserialization