用Javascript實現Command模式

command|javascript

這個實現實在太簡單了………動態語言就是好使啊~
先定義一個Command對象，代碼如下：

function Command(obj) {
    var commandObj = obj;       // save the reference of working object
    var oldProp = new Object(); // save old properties
   
    // set new properties and save old properties
    this.Do = function() {
        for (var o in this) {
            oldProp[o] = commandObj[o];
            commandObj[o] = this[o];
        }
    }
   
    // restore old properties
    this.Undo = function() {
        for (var o in oldProp) {
            commandObj[o] = oldProp[o];
        }

        delete oldProp;
        oldProp = new Object();
    }
}

如果要調用，這樣寫就可以了：

// "mc" is an object that has _alpha and _x attributes

var com = new Command(mc);
com._alpha = 20;
com._x = 200;
com.Do();
// do something...
// remember to save this Command somewhere...

// now, undo it!
com.Undo();

為這樣的簡單而和諧 驚歎了！