Dark clouds related to PHP callback functions

Dark clouds about PHP callback functions. I am a good expert. could you tell me how to use the EventStack yywatcher method in PHP to return the obtained data to welcome. where did I write the callback function specified by php ;??? The error is: Fatal & the dark clouds related to the PHP callback function.
I am a good expert. could you tell me how to use the EventStack yywatcher method in PHP to return the obtained data to welcome. where did I write the callback function specified by php ???

Error: Fatal error: Function name must be a string in/home/latel/Workspace/new_zhebo/module/EventStack. php on line ××

/App/welcome. php

  
If (! Defined ("_ IS_ROOT") die ("Access Denied ");
 
Global $ EventStack;
 
// Closure function (callback)
$ FGetSettings = function ($ oSettingDaemon ){
// Set the data model for the system returned by processing the callback
Echo $ oSettingDaemon;
};
 
// Request data prototype
$ EventStack-> addEvent (
"DATA_REQUEST ",
Serialize (array (
Array (
"Request" => "settingDaemon"
)
)),
$ FGetSettings,
Null
);
?>

/EventStack. php

 // Event stack processing component
/* Number
*/
// Known event stamps
/*
*/
 
If (! Defined ("_ IS_ROOT") die ("Access Denied ");
 
Class EventStack extends Init {
Private $ _ aWatcherRegistry = array (); // list of registered observers
Private $ _ aEventStack = array (); // event stack
Private $ _ aCallbackRegistry = array (); // registered callback function
 
Function _ construct (){
}
Function _ destruct (){
// Store key information to the Log table of the data source
// Determine whether to output the debugging information to the page based on the debugging switch.
}
Function _ toString (){
}
# ##
Public function addEvent ($ sStamp = "ISSUE_TRACK", $ sValue, $ fHandler = null, $ msler = null ){
/* SStamp: the message stamp.
* SValue: serialized array
* FHandler (function): Anonymous callback function
* MScope (mixed type): context of the callback function,
* Null indicates that the passed handler function is a global function,
* The String type indicates that the input handler function is a static function of the scope class,
* The object type indicates that the passed scope is an object, and the handler function is a method of the object.
*/
$ This-> _ aEventStack [] = array (
"Stamp" => $ sStamp,
"Value" => $ sValue,
"Handler" => $ fHandler,
"Scope" => $ mScope,
"Timestamp" => time ()
);
$ IKey = sizeof ($ this-> _ aEventStack)-1;
$ This-> policywatcher ($ iKey );
Return $ iKey;
}
Public function addWatcher ($ oWatcher, $ sWatchStamp ){
}
# C ##
Public function clearEventStack (){
// Clear the event stack
}
# E ##
Public function exportEventStack (){
// Output debugging information
}
# G ##
Public function getStack ($ iStackId ){
// Return the stack list or specified stack content based on whether the stack sequence number is provided
}
# N ##
Private function notifyWatcher ($ iKey ){
// Push the event to the corresponding observer
If (array_key_exists ($ this-> _ aEventStack [$ iKey] ["stamp"], $ this-> _ aWatcherRegistry )){
$ MCallback = $ this-> _ aWatcherRegistry [$ this-> _ aEventStack [$ iKey] ["stamp"] (
$ This-> _ aEventStack [$ iKey] ["stamp"],
$ This-> _ aEventStack [$ iKey] ["value"],
$ This-> _ aEventStack [$ iKey] ["handler"],
$ This-> _ aEventStack [$ iKey] ["scope"]