Protocol method

Intent

Implement a set of related operations

Motivation

Define different iteration strategies, across different inheritance hierarchies, similar to interface, but allows for differnt fuctions to implement the interface specification

Implementation

Define a method returning the required functions by the interface

Examples

class alt_iterator {
  private $st = array();

  function next() { ... }
  function current() { ... }
  function valid() { ... }
  //... put the rest here

  function protocol() {
    return array(
             array($this,'next'),
             array($this,'current'),
             array($this,'valid'),
	     .....
	     );
  }  
}

//an example use: iterator protocol
function do_them($itor, $callback ) {
  list($next, $current, $valid, ...) = $itor->protocol();
  while($valid) {
    $callback( $current );
    $next();
  }
}