PHP how to set static variable from a string

Question

Is it possible to be able to dynamically set a php static class variable? In the example below i want to pass a string representation of the variable i want to set to a function "databaseInit" which then sets the var...

class app {
    static $database_smf;
    static $database_phpbb;

    /**
     * Initialise the app
     */
    static function init(){

        // No initialise the db connection
        self::databaseInit('database_phpbb');
        self::databaseInit('database_smf');

    }

    static function databaseInit( $database ){
        // is it possible to dynamically set the static var based on the param provided? eg:
        self::[$database] = true;
    }
}

Possible duplicate of Getting static property from a class with dynamic class name in PHP — MatsLindh
– MatsLindh, Commented Feb 26, 2017 at 10:22
The question you linked is not straight forward and neither are the answers. So, technically yes, but i would say this question will assist others getting to the bottom of the issue with much more efficiency :D — user1037355
– user1037355, Commented Feb 26, 2017 at 10:32

MatsLindh · Accepted Answer · 2017-02-26 10:21:58Z

0

You can use a plain variable variable name:

static function databaseInit( $database ){
    self::$$database = true;
}

.. but you should really rework it to just keep an array and manipulate the keys of the array instead, as that will keep all the settings inside a single namespace instead of potentially doing weird stuff with other static variables if a name is mistyped, etc.

class app {
    static $databases = [];

    ...

    static function databaseInit($database) {
        self::$databases[$database] = true;
    }
}

And the next step would be to make the class non-static instead, so it can be easier tested and will keep its state locally instead.

answered Feb 26, 2017 at 10:21

MatsLindh

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1 Comment

user1037355 Over a year ago

ah of course yes! variable variable! Perfect thanks!

Dorad · Accepted Answer · 2017-02-26 10:20:56Z

0

Yes that is possible. Just a little change in your code:

Use:

self::$$database = true;

Instead of:

self::[$database] = true;

class app {
    static $database_smf;
    static $database_phpbb;

Full code:

    /**
     * Initialise the app
     */
    static function init(){

        // No initialise the db connection
        self::databaseInit('database_phpbb');
        self::databaseInit('database_smf');

    }

    static function databaseInit( $database ){
        // is it possible to dynamically set the static var based on the param provided? eg:
        self::$$database = true;
    }
}

answered Feb 26, 2017 at 10:20

Dorad

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