PHP const defined

Question

Why does the following code give me an exception saying that my constant isn't defined

MyClass::myFunction(MyClass::MY_CONST); // THIS GIVES THE ERROR   

// This is the class..
class MyClass {

    const MY_CONST = 'BLA';

    public static function myFunction($key) {
        if (!defined($key)) {
            throw new Exception("$key is not defined as a constant");
        }
    }
}

I've tried with

• if (!defined($key)) {}
• if (!defined(self::$key)) {}
• if (!defined(__CLASS__ . $key)) {}

Answer 1

You have to pass it as a string:

public static function myFunction($key) {
    if (!defined('self::'.$key)) {
        throw new Exception("$key is not defined as a constant");
    }
}


MyClass::myFunction('MY_CONST');