使用PHP中的对象函数调用链接构造函数

Question

Does anyone know if the following expression will be possible in the next version(s) of PHP?

(new A())->a();    // Causes a syntax error

I find very annoying that currently one must write 2 lines instead of 1:

$c = new A();
$c->a();

Answer 1

The first version does not cause a parse error, it is perfectly valid. The second it is, indeed not possible, but you can easily overcome such a problem with some coding standards.

If every team member creates, for each defined class, a function with the same name as the class, and a signature similar to the signature of the class constructor, then you won't have the second problem. Example:

class Foo
{
    public function __construct($param)
    {}

    public function bar()
    {}
}

/**
 * @return Foo
 */
function Foo($param)
{
    return new Foo($param);
}

Foo()->bar();

Of course, you'll still have problems with library code.

Answer 2

A new-expression can be used as a function argument. A function call can be used as the left-hand side of the member access operator. Therefore, you just need to define a single function:

function with($object) { return $object; }

with(new A()) -> a();

No additional efforts required on a per-class basis.

Answer 3

This is possible as of PHP 5.4+ :

Class member access on instantiation has been added, eg (new Foo)->bar().