(PECL event >= 1.2.6-beta)
EventListener::setCallback — The setCallback purpose
Adjust event connect listener's callback and optionally the callback argument.
cb
    
      The new callback for new connections. Ignored if NULL.
     
Should match the following prototype:
$listener
        = NULL
      
      [, 
       mixed
        $fd
        = NULL
      
      [, 
       array
        $address
        = NULL
      
      [, 
       mixed
        $arg
        = NULL
      
     ]]]] )
listener
        The EventListener object.
fd
        The file descriptor or a resource associated with the listener.
address
        Array of two elements: IP address and the server port.
arg
        User custom data attached to the callback.
arg
    
      Custom user data attached to the callback. Ignored if NULL.
     
No value is returned.