Constant in PHP class and "static" keyword

Question

Please consider this code:

    class App {

        const ALERT_ERROR=1;
        const ALERT_WARN=2;
        const ALERT_INFO=3;

        public static function alert($title,$type=ALERT_ERROR) {        
            switch ($type){
                default:                
                case static::ALERT_ERROR:
                    $class="alert-danger"; break;
                case static::ALERT_WARN:
                    $class="alert-warning"; break;
                case static::ALERT_INFO:
                    $class="alert-info"; break;
            }
            ...
        }
    }

I have some trouble with the static::constant syntax inside the switch. I some PHP webserver it is recognized as correct value (as defined in const ALERT_ERROR) in other server I had to remove the static:: prefix and leave only the constant name. But with this way the first webserver doesn't work...

The first php version is 5.4.7 the second is 5.4.37... but I don't think this is version problem.

The problem is that if I run this code:

App::alert("test",App::ALERT_INFO);

the $class is set a "alert-danger" as default, and the App::ALERT_INFO constant is not recognized. If I add static:: prefix the constant is recognized from one webserver and not from the other and viceversa if I remove it.

The notice thrown is: Use of undefined constant ALERT_ERROR - assumed 'ALERT_ERROR'

EDIT after the answer

The problem was not in the switch cases but in the default parameter. That was assumed as "ALERT_ERROR" string and so only the default switch was got.

Before closing your question try to explain how exactly it's not working — u_mulder
– u_mulder, Commented Mar 1, 2015 at 11:21

Yahya Uddin · Accepted Answer · 2015-03-01 12:21:33Z

14

You have to add the static keyword to the constant used as default value.

public static function alert($title, $type=static::ALERT_ERROR) {
  // ....
}

But static is only determined at runtime. So if static behaviour is really needed then:

public static function alert($title, $type=null) {
  if ($type === null) {
      $type = static::ALERT_ERROR;
  }
  // ...
}

If static is not really necessary then replace all static:: as self::

   public static function alert($title, $type=self::ALERT_ERROR) {        
    switch ($type){
        default:                
        case self::ALERT_ERROR:
            $class="alert-danger"; break;
        case self::ALERT_WARN:
            $class="alert-warning"; break;
        case self::ALERT_INFO:
            $class="alert-info"; break;
    }
    ....
}

edited Mar 1, 2015 at 12:21

Yahya Uddin

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answered Mar 1, 2015 at 11:29

Maks3w

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5 Comments

Tobia Over a year ago

Fatal error: "static::" is not allowed in compile-time constants

Tobia Over a year ago

This seems to be the answer, but I have to set a different param default value.

Maks3w Over a year ago

Ok. Do you really need static? If not use self. static is for inheritance override

Yahya Uddin Over a year ago

Please edit answer to reflect correct answer, as using static here gives fatal error!

Tobia Over a year ago

In this particular case I can also use null as default param because the it is used only in the case switch so it is catched by the "default" case. Thanks.

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