什么是PHP函数重载？

Question

In languages like Java, overloading can be used in this way:

void test($foo, $bar){}
int test($foo){}

Then if you called test() with 2 arguments e.g test($x, $y);, the first function would be called. If you passed only 1 argument e.g test($x);, the 2nd function would be called.

From the manual it seems that php 5 does have overloading, but what is it for? I can't seem to understand the manual on this topic..

Answer 1

PHP's meaning of overloading is different than Java's. In PHP, overloading means that you are able to add object members at runtime, by implementing some of the __magic methods, like __get, __set, __call, __callStatic. You load objects with new members.

Overloading in PHP provides means to dynamically "create" properties and methods. These dynamic entities are processed via magic methods one can establish in a class for various action types.

An example:

class Foo
{
    public function __call($method, $args)
    {
        echo "Called method $method";
    }
}

$foo = new Foo;

$foo->bar(); // Called method bar
$foo->baz(); // Called method baz

And by the way, PHP supports this kind of overloading since PHP 4.3.0. The only difference is that in versions prior to PHP 5 you had to explicitly activate overloading using the overload() function.