OOP -> interfaces

• The Interfaces are abstract classes, which was declared but not defined.
• we can not create object of Interfaces.
• To use interfaces, we use "implements" keyword.
• Interfaces have empty functions which you have to defined during the implement. 
• You have to defined all the functions during the implements.
• Interfaces are 100% blueprint that tell what function you must defined.
• We can implements one or more class during in-heritance.

Following are the Example of Interfaces

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

// Implement the interface
// This will work
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;
    }
}