dess中一个简单的多路委托的实现

复制代码 代码如下:

  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。