__init magic method

@Pete just FYI, PSR-1 excludes that such a logic should exist in a loaded
file:

https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-1-basic-coding-standard.md#23-side-effects

Not sure if you are interested in following the FIG on these ideas, but the
guideline makes actually sense.

Marco Pivetta

http://twitter.com/Ocramius

http://ocramius.github.com/

I am actually going to +1 this idea I thought about discussing it, but
opted out of it because classes are most often in their own file and if you
need to do some static binding you can do it at the end of the file after
the class definition. However, I do believe this idea would make it easier
to extend classes and make the code look much cleaner.

@Johannes In your example I'd say it would be ADBCE because I would say it
should work like as if you had each one in it's own file autoloading them.
(also I believe the function would be static)

One of the potential problems I can see is the visibility
(public/private/protected) of the function as it'd likely need to be public
because it could never be auto-executed if anything else.

Software Developer
Nathan Bruer

-----Original Message-----
From: Johannes Schlüter [mailto:johannes@php.net]
Sent: Tuesday, January 22, 2013 7:04 AM
To: Pete Boere
Cc: internals@lists.php.net
Subject: Re: [PHP-DEV] __init magic method

Hi,

Has there ever been any discussion on an __init magic method for
bootstraping static properties on class load?

Adding an __init method as you wish will just add complexity and gain very
little. What complexity am I talking about? Well look at this single file:

<?php
class A {
public function __init() { echo CLASS; }
}
class B extends D {
public function __init() { echo CLASS; }
}
class C {
public function __init() { echo CLASS; }
}
class D {
public function __init() { echo CLASS; }
}
class E {
public function __init() { echo CLASS; }
}
?>

What should this print? ABCDE? Then the derived class B is initialized
before the base class D, which might have strange effects and make
debugging hard. So maybe it is ACDEB? This makes the resolution quite
complicated.

On the other hand: You are showing a goos solution, which is clear and
works well. PHP has the global scope, we don't force everything into
classes and then create Java-style static{}-madness.

johannes

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I am actually going to +1 this idea I thought about discussing it, but
opted out of it because classes are most often in their own file and
if you need to do some static binding you can do it at the end of the
file after the class definition. However, I do believe this idea would
make it easier to extend classes

How so?

and make the code look much cleaner.

Thankfully that's subjective. Some people prefer explicit information
which can easily be read over magic, though.

@Johannes In your example I'd say it would be ADBCE because I would
say it should work like as if you had each one in it's own file
autoloading them. (also I believe the function would be static)

In other words: It is called at completely arbitrary times. Which makes
reading code hard as well as making the implementation more complex
(dependency detection)

Mind that your order requires the engine to delay initialization of B
and C (and E) till D is found. And then go back. That's why I listed the
version with B in the end, that's a tiny bit simpler to implement, but
as hard to explain.

Now for a second game: What does the following script print?

<?php
echo "A";
class foo { static function __init() { echo "B"; } }
echo "C";
?>

ABC? ACB? BAC? I guess the later as the code next to A or C might depend
on the class already.

I hope you see the mess this creates, whereas we nowadays have a
solution which is properly defined and can easily be understood by
everybody, even by people coming from other languages and just trying to
understand the code which was put in front of them.

One of the potential problems I can see is the visibility
(public/private/protected) of the function as it'd likely need to be
public because it could never be auto-executed if anything else.

Such things would be trivial to check during compilation phase.

johannes