Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:109302
MIME-Version: 1.0
Date: Wed, 25 Mar 2020 13:51:31 -0300
Message-ID: <CAEsg9X3cNkcSthzjpgD+r5BJ=V19hOa_PUkcaf-TOtWcZ7tXUA@mail.gmail.com>
To: PHP Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="000000000000ddd67705a1b0aebc"
Subject: Class cast
From: david.proweb@gmail.com (David Rodrigues)

--000000000000ddd67705a1b0aebc
Content-Type: text/plain; charset="UTF-8"

Currently PHP supports generic castings like (string), (int), ... maybe is
time to allow class castings like (ToClass) $fromObject?

I think that it could be useful to converts to another kind of structure,
or even to reduce object type.

For instance:

---

1. Converting from A to B:

$a = 123;
$b = (Number) $a; // $b is now instanceof Number

A instanceof Number will created based on $a value.

---

2. Reduce object type (I don't know the technical term):

class A {}
class B extends A {}

$b = new B;
$a = (A) $b;

$a still is $b, but with "limited" access to A methods and properties.

---

To make possible custom some kind of castings, I suggests a new magic
method __cast($value).

class Number {
    ...
    function __cast($value) {
        if (is_int($value) || is_float($value)) return new static($value);
        throw new TypeError();
    }
}

Just to talk.


Atenciosamente,
David Rodrigues

--000000000000ddd67705a1b0aebc--