is_initialized.php

<?php
class Foo {
    private int $property;

    public function __construct() {
        $this->reflector = new ReflectionProperty($this, "property");
        $this->reflector->setAccessible(true);
    }

    public function test() {
        return is_initialized($this, "property");
    }

    public function testReflection() {
        return $this->reflector->isInitialized($this);
    }
}

$foo = new Foo;
$iterations = 1000000;

$start = microtime(true);
for ($count = 0; $count < $iterations; $count++)
    $foo->test();
printf("is_initialized: %.5f seconds\n", microtime(true)-$start);


$start = microtime(true);
for ($count = 0; $count < $iterations; $count++)
    $foo->testReflection();
printf("reflection: %.5f seconds\n", microtime(true)-$start);
?>