event based timer

[Daniel Murphy]

private void  function() *  callBack;

should be private void  function() callBack;

void function() is a function pointer, void function()* is a pointer to a 
function pointer.

On lines 23 and 41, you shouldn't be dereferencing callBack.  Just use 
callBack() to call the function and 'this.callBack = callBack' to set it.