A possible way to simulate mixins in PHP

mixins.php

<?php

class Person {

	private $mixins = array();
	private $instances = array();

	public function __construct()
	{
		if (func_num_args())
		{
			foreach(func_get_args() AS $mixin)
			{
				$reflection = new ReflectionClass($mixin);
				$methods = $reflection->getMethods();

				foreach($methods AS $method)
				{
					$this->mixins[$method->name] = array('class' => $mixin);
				}
			}
		}
	}

	public function __call($name, $arguments)
	{
		if (isset($this->mixins[$name]))
		{
			if ( ! isset($this->instances[$this->mixins[$name]['class']]))
			{
				$this->instances[$this->mixins[$name]['class']] = new $this->mixins[$name]['class'];
			}

			call_user_func_array(array($this->instances[$this->mixins[$name]['class']], $name), $arguments);
		}
		else
		{
			throw new Exception('Method not found');
		}
	}

	public function walk()
	{
		print 'A person can walk'.PHP_EOL;
	}
}

class WaiterMixin {

	private static $at;

	public function __construct()
	{
		self::$at = microtime(TRUE);
	}

	public function say($something = '')
	{
		if ($something)
		{
			print 'The waiter would say it like this: '.implode(' and ', (array) $something).PHP_EOL;
		}
		else
		{
			print 'The waiter mixin was instantiated at '.self::$at.'. A waiter would say "Vodka sir?"'.PHP_EOL;
		}
	}

	public function wave()
	{
		print 'The waiter mixin was instantiated at '.self::$at.'. A waiter waves like this \/'.PHP_EOL;
	}
}

class MechanicMixin {

	public function say($something = '')
	{
		if ($something)
		{
			print 'The mechanic would say it like this: '.implode(' and ', (array) $something).PHP_EOL;
		}
		else
		{
			print 'Alright Guv, this needs a new exhaust'.PHP_EOL;
		}
	}
}

$person = new Person('WaiterMixin', 'MechanicMixin');
$person->walk();
$person->say();
$person->wave();