import debug for debug; 

class event { 
    func init() {
        self._func = [];  // callback functions list
    }
    
    func clear() {
        self._func.clear();
    }  
    
    func += (fn) {
        if(typeof(fn) != "function") 
            debug.assert("wrong type");
        if(!self._func.contains(fn))
            self._func.push(fn); 
        else 
            debug.logError("已经存在这个方法");
    } 
    
    func -= (fn) { 
        if(typeof(fn) != "function") 
            debug.assert("wrong type");
        self._func.remove(fn); 
    } 
    
    func () (...){ 
        foreach(var fn in self._func) {
            fn(...);
        } 
    } 
} 

/*
var Say = new event(); 
Say += func(str) { 
    io.print(str);
} 
Say("hi");
Say.clear();

*/