Interfaces

Hi Muhammad.

In my own words, an interface is a declaration of a class and its methods. These methods would be "empty", therefore having no functionality. Below is an exmaple of an interface's method.

public function setVariable($name, $var);

As you can see this is purely just a declaration, there is no functionality within this function....yet! Let now build a simple PHP interface.

interface iTemplate {
    public function setVariable($name, $var);
    public function getHtml($template);
}

The idea behind PHP interfaceS is to act as a sort of Class template. You build an interface, you specify methods within this interface, then any class that wants to use this interface is required to implement the methods functionality. Below is a further example of how a class would use our above interface.

class Template implements iTemplate{
    private $vars = array();

    public function setVariable($name, $var) {
        $this->vars[$name] = $var;
    }

    public function getHtml($template){
        foreach($this->vars as $name => $value) {
            $template = str_replace('{' . $name . '}', $value, $template);
        }

        return $template;
    }
}

As you can see each of the method defined in the interface have been implemented int he template class. PHP would throw fatal error if you were not to implement all of an interfaces methods.

Hope this helps, Scott.