Preventing Methods From Being Invoked Via The URL

Sometimes you may not want some of your methods to be accessible via the URL.  For those situations, there are three ways to prevent your methods from being invoked (accessed / triggered) via the URL. They are:

Method One: Private Methods

A private method is a method that can only be invoked when it is called directly from within the class where it resides. In PHP, a method can be made private by simply adding the word 'private' before the function declaration. For example:

private function apply_discount($price) {

    if ($price>100) {
     $discount = $price*0.2;
     $price = $price - $discount;
    }

    return $price;
}

Method Two: Protected Methods

A protected method is a method that can be invoked within its parent class and by classes derived from that class. Methods can be made to be protected by simply adding the word 'protected' before the method declaration. For example:

protected function apply_discount($price) {

    if ($price>100) {
        $discount = $price*0.2;
        $price = $price - $discount;
    }

    return $price;
}

Method Three: The Underscore Shortcut

An easier and faster way to make methods impossible to invoke via the URL is simply to make the first character of the method name an underscore. For example:

function _apply_discount($price) {
    
    if ($price>100) {
        $discount = $price*0.2;
        $price = $price - $discount;
    }

    return $price;
}