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Date: Thu, 12 Mar 2015 09:54:12 +0100
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Subject: Re: [PHP-DEV] static constructor
From: mail@deroetzi.de (Johannes Ott)

Am 12.03.2015 um 05:17 schrieb Levi Morrison:
> On Wed, Mar 11, 2015 at 6:10 PM, Rowan Collins <rowan.collins@gmail.com> wrote:
>> On 11/03/2015 23:21, Johannes Ott wrote:
>>>
>>> So now I want to do my first own proposal for a new function in PHP and
>>> I hope doing it right with starting a discussion here first.
>>>
>>> The purpose of this suggestion is to introduce a static constructor,
>>> which is called before the first call to class either static or
>>> non-static to initialize some static properties which are needed by the
>>> class.
>>
>>
>> Can you give an example use case for when this would be useful? I'm
>> struggling to think of one for which there isn't already an established
>> coding pattern...
> 
> Notably, user-land enums. You don't want public constructors because
> you don't want it instantiated except for each enum property. You also
> need it to run on class creation, not afterwards.
> 
> I think we'd be better off adding language-level enums than static
> constructors though.
> 

Yes indeed user-land enums are one of the use cases I use this feature
at the moment. But there some other use cases as well:

1. Nearly all of my classes have a static LogAdapter $LOG which has to
be intialized with Classname once.

class A {
    private static $LOG;

    public static function __static() {
        self::$LOG = LogAdapter::getLogger(self::class);
    }
} A::__static();

The LogAdapter by it selfs although have a __static() method to prepare
the Log4PHP-Framework I'm using.

2. Some Config classes which are intelligent wrapper-classes to some
ini-files and database have to read in some things first.

class Config {

    private static $ini;

    public static function __static() {
	self::$ini = parse_ini_file(...);
	// or
        // Read from Database

    }

} Config::__static();

3. For a multilanguage system I determine the user language by useragent
and fallback to default-language if user language ist not supported.

class Text {
    private static $defaultLang;

    private static $userLang;

    public static function __static() {
        self::$defaultLang = //read from Database
        self::setUserLanguageOrFallback();
    }

    private static function setUserLanguageOrFallback() {
        ...
    }
} Text::__static();

4. Already prepare some PDO-statements which needed all over the class

class Example {
   private static $stmts = [];

   public static function __static() {
	self::$stmts['select1'] = new DBSelect('SELECT * FROM table WHERE
`col1`=:clause');
   }
} Example::__static();

That are the examples I can found on a quick search over my code.

Regards,

-- 
DerOetzi