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Date: Sat, 17 Jan 2015 10:56:19 -0700
Message-ID: <CAFMT4NrH+=6B4=kVyrmW1Oc0N-_ONNdjaWK0xZCXDVnV_pn-Nw@mail.gmail.com>
To: Tony Marston <TonyMarston@hotmail.com>
Cc: internals <internals@lists.php.net>
Content-Type: text/plain; charset=UTF-8
Subject: Re: [PHP-DEV] [RFC] Remove PHP 4 Constructors
From: levim@php.net (Levi Morrison)

>> We are talking about something deprecated since 10 years, about the 1st
>> major release in a decade, something we will use for the next 12-14 years.
>
>
> That is the point - PHP 4 constructors have NOT been marked as deprecated in
> the manual, and they produce no warnings at runtime.
>
> If they have not been marked as deprecated then you cannot suddenly remove
> them.

Warning: a long response with code snippets/

See this code (http://3v4l.org/ViPpb):

    class Test {
       function test() {
            echo __METHOD__, PHP_EOL;
        }
       function __construct() {
           echo __METHOD__, PHP_EOL;
        }
    }

    new Test();

Note that there is an E_STRICT generated for having both constructor
types in all versions of PHP 5 and that `__construct` is actually used
as the constructor.

Now if you change the order of the definitions around (http://3v4l.org/BhPMm):

    class Test {
       function __construct() {
           echo __METHOD__, PHP_EOL;
        }
       function test() {
            echo __METHOD__, PHP_EOL;
        }
    }

    new Test();

Note that `__construct` is still used and the E_STRICT is only
generated in PHP 5.0-5.3 (roughly; it's a bit more nuanced).

If you put a namespace at the top of the first example(http://3v4l.org/hWFnC):

    namespace NS;

    class Test {
       function test() {
            echo __METHOD__, PHP_EOL;
        }
       function __construct() {
            echo __METHOD__, PHP_EOL;
        }
    }

    new Test();

Then there are no warnings of any kind (since PHP 5.3.2), and
__construct is used as the constructor. The method test is just a
normal method.

To me this clearly indicates three things:

  1. Having both forms of constructors is bad form (hence the E_STRICT)
  2. When both are present the new-style __construct is used over the
old-style PHP 4 constructor, meaning the language prefers
__constructor.
  3. Old-style constructors don't exist in namespaces. Notably this
was a conscious choice as evidenced by behavior that existed in PHP
5.3.0 - 5.3.2 where the E_STRICT was emitted like non-namespaced code.

This is the behavior of shipped, stable versions of PHP. I think it's
a bit illogical to conclude that just because there aren't any
E_DEPRECATED warnings emitted in PHP 5 that old-style constructors are
fully supported.

That leaves us realistically with four options:

  1. Bring full support for PHP 4 constructors
  2. Emit E_DEPRECATED when PHP 4 constructors are used
  3. Drop support for PHP 4 constructors so they are just normal
methods, just as they are in namespaces
  4. Maintain current behavior.

As already mentioned I think as an end result we shouldn't have two
ways to define constructors. Given that PHP already prefers the
new-style constructors I've proposed that we work towards dropping the
old-style, it's just down to a matter of how.