registerFooCallbacks

example.js

// Scans an object for WSH-Panel callbacks, and registers them.
function registerFooCallbacks(obj)
{
    if(!(obj instanceof Object))
        return false;
        
    // grab a reference to the global context
    var global = (function() { return this; })();
        
    for(var attr in obj) {
        if(attr.indexOf("on_") != 0)
            continue;
        
        // Check if we have not already created our handler for this callback type.
        // Check first if there's a version of the callback in the global scope.
        // If affirmative, check if it's actually ours, and if it's not, save the 
        // current function, so it can still be called later.
        
        var original_func = null;
        if(typeof global[attr] == 'function') {
            if('callback_objs' in global[attr]) {
                global[attr].callback_objs.push(obj);
                continue;
            }
            
            original_func = global[attr];
        }   
        
        // We need a wrapper taking attr as an argument to capture it by value,
        // not reference.        
        global[attr] = (function(attr) {
            var f = function() {
                var original_func = arguments.callee.original_func;
                if(typeof(original_func) == 'function')
                    original_func.apply(global, arguments);
                    
                var callback_objs = arguments.callee.callback_objs;
                if(callback_objs) {
                    for(var i = 0; i < callback_objs.length; i++) {
                        var obj = callback_objs[i];
                        if(!(obj instanceof Object)) {
                            callback_objs.slice(i, 1);
                            
                            i--;
                            continue;
                        }
                        
                        if(typeof obj[attr] == 'function')
                            obj[attr].apply(obj, arguments);
                    }
                }
            };
            return f;
        })(attr);
        
        global[attr].callback_objs = [obj];
        global[attr].original_func = original_func;
    }
    
    return true;
};

// What follows is example code: if you just want to test you can copy everything into a WSH-Panel instance,
// otherwise skip everything below this line.

function MyPlayMonitor(id)
{
    this.id = id;
    registerFooCallbacks(this);
};
MyPlayMonitor.prototype.on_play_order_changed = function(new_order_index)
{
    fb.trace("Play order changed! (id = " + this.id + ")");
};
MyPlayMonitor.prototype.on_playback_pause = function(state)
{
    fb.trace("Playback state changed! (id = " + this.id + ")");
};

function on_playback_pause(state)
{
    fb.trace("Global callback, reporting for duty.");
};

var play_orders = [new MyPlayMonitor("foo"), new MyPlayMonitor("bar")];

registerFooCallbacks.js

// Scans an object for WSH-Panel callbacks, and registers them.
function registerFooCallbacks(obj)
{
    if(!(obj instanceof Object))
        return false;
        
    // grab a reference to the global context
    var global = (function() { return this; })();
        
    for(var attr in obj) {
        if(attr.indexOf("on_") != 0)
            continue;
        
        // Check if we have not already created our handler for this callback type.
        // Check first if there's a version of the callback in the global scope.
        // If affirmative, check if it's actually ours, and if it's not, save the 
        // current function, so it can still be called later.
        
        var original_func = null;
        if(typeof global[attr] == 'function') {
            if('callback_objs' in global[attr]) {
                global[attr].callback_objs.push(obj);
                continue;
            }
            
            original_func = global[attr];
        }   
        
        // We need a wrapper taking attr as an argument to capture it by value,
        // not reference.        
        global[attr] = (function(attr) {
            var f = function() {
                var original_func = arguments.callee.original_func;
                if(typeof(original_func) == 'function')
                    original_func.apply(global, arguments);
                    
                var callback_objs = arguments.callee.callback_objs;
                if(callback_objs) {
                    for(var i = 0; i < callback_objs.length; i++) {
                        var obj = callback_objs[i];
                        if(!(obj instanceof Object)) {
                            callback_objs.slice(i, 1);
                            
                            i--;
                            continue;
                        }
                        
                        if(typeof obj[attr] == 'function')
                            obj[attr].apply(obj, arguments);
                    }
                }
            };
            return f;
        })(attr);
        
        global[attr].callback_objs = [obj];
        global[attr].original_func = original_func;
    }
    
    return true;
};