I would like to do something like this: 

class example { 
function print_a_list ( $an_array ) 
{.......} 

function do_something { 
{.... 
array_walk( fruits, "$this->print_a_list" ); 
....} 
} 

The error returned is 
Warning: Unable to call () - function does not exist in inc\example_class.php 

To get it working I have done this 

class example { 

function do_something { 
{ 
  if(!defined('PRINT_FUNCTION')) 
  { 
    define('PRINT_FUNCTION', TRUE); 
    function print_a_list ( $an_array ) 
    {.......} 
  } 
  .... 
  array_walk( fruits, "print_a_list" ); 
  .... 
} //end do_something 
} //end example class 

The define is to stop errors when I call the do_something method more than once for a single instance of the example class. If I don't it gives me a Cannot Redelare error. 
This is not really perfect becasue I have to declare print_a_list twice if I want to use it outside the do_something function.  Plus the code is abit messy. 

I've asked experts-exchange.com and studied the docs but I can find a way around it.  I've also tried it using php4 with the same results.
Thanks for your time,
Tim.