How can I indicate that a parameter in a php function has a type of determined class using the phpDoc?

Question

In this example:

/**
 *
 * @param <type> $foo
 * @return <type> 
 */
function do_something($foo) {
    return $foo->really_do_something();
}

How to indicate that $foo must be of the class Foo?

Answer 1

/**
 *
 * @param Foo $foo
 * @return <type> 
 */
function do_something(Foo $foo) {
    return $foo->really_do_something();
}

Answer 2

More recent versions of PHP (PHP 5 onwards I think) have parameter types:

function do_something(Foo $foo) {
   return $foo->really_do_something();
}

Which will throw an exception if $foo is not a type of Foo.

I assume phpDoc picks this up