Fat-Free-Framework global variables and functions

Question

I'm new to fat free framework and i'm a little bit confused about the global variables.

$f3->route('GET /@page','display');

    function display($f3) {
        echo 'I cannot object to an object' . $f3->get('PARAMS.page');
    };

$f3->run();

Here i'm using GET /@page as a token for the url route. In the function i then use $f3->get('PARAMS.page') to get the value of that variable.

Since $f3->get is the method to get a global variable, why do i have to pass the $f3 class to the function.

The below code doesn't work ($f3 class not passed to the function).

$f3->route('GET /@page','display');

    function display() {
        echo 'I cannot object to an object' . $f3->get('PARAMS.page');
    };

$f3->run();

So my question is: why do i have to pass the $f3 class to the function?

Thx...

Answer 1

The F3 instance variable which is declared at the very start of your index.php ($f3=require...) can be retrieved anywhere in the code using the static call $f3=Base::instance().

Anyway, for convenience purpose, at routing time this F3 instance as well as the route parameters are passed to the route handler. Therefore, instead of defining your route handler as:

function display() {
    $f3=Base::instance();
    echo 'I cannot object to an object' . $f3->get('PARAMS.page');
};

you could define it as:

function display($f3) {
    echo 'I cannot object to an object' . $f3->get('PARAMS.page');
};

or even better:

function display($f3,$params) {
    echo 'I cannot object to an object' . $params['page'];
};

These 3 functions are absolutely identical so you should pick up the one that you understand best. But you should remember that $f3 and $params are only passed at routing time, which means to 3 functions: the route handler, the beforeRoute() hook and the afterRoute() hook. Anywhere else in the code (including inside a class constructor), you should call Base::instance() to retrieve the F3 instance.

PS: your question being "why do i have to pass the $f3 class to the function?", I would suggest you to rename its title to reflect it.

UPDATE: Since release 3.2.1, the F3 instance is also passed to the constructor of the route handler class:

class myClass {
    function display($f3,$params) {
        echo 'I cannot object to an object' . $params['page'];
    }
    function __construct($f3) {
        //do something with $f3
    }
}