dess中一个简单的多路委托的实现_javascript技巧

var SDelegate = function(f, b, c) {
if (b) {
this.asFunction_ = function() {
return f.apply(b, arguments);
}
} else {
this.asFunction_ = function() {
return f.apply(this, arguments);
}
}
this.method_ = f;
this.binding_ = b;
this.continus = c;
}
SDelegate.composite = function(d) {
if (d.continus) {
var con = d.continus.composited_ = SDelegate.composite(d.continus);
var method = d.asFunction_;
return function() {
con.apply(this, arguments);
return method.apply(this, arguments);
}
} else {
return d.asFunction_;
}
}
SDelegate.prototype.call = function() {
if (!this.composited_) this.composited_ = SDelegate.composite(this);
return this.composited_.apply(arguments[0], Array.prototype.slice.call(arguments, 1));
}
SDelegate.prototype.remove = function() {
var removeP = function(parent, item, test, data) {
if (!item) return;
parent.composited_ = item.composited_ = null;
if (test(item, data)) {
parent.continus = item.continus;
removeP(parent, item.continus, test, data);
} else {
removeP(item, item.continus, test, data);
}
};
return function(test, data) {
var p = this;
if (test(this, data)) {
p = this.continus;
}
removeP(p, p.continus, test, data);
p.composited_ = null;
return p;
}
}();
SDelegate.prototype.append = function(f, b) {
return new SDelegate(f, b, this);
}

这个SDelegate用起来可能会比较诡异，比如很多操作都要重新赋值。Dess中，SDelegate主要用于一些特定场合，如DOM事件派发。