// Professional Javascrip for Webdevelopers - page 177
// working example using object literal declaration and defineProperty()
//
// i just changed a logic a bit, so when the new version of the book
// is released in 2007, it becomes 2nd edition not 4th (1 + 2007 - 2004)
// as it is in the example in the book

var book = {};
book = {
    _year: 2004,
    edition: 1
};

Object.defineProperty(book, "year",{
    get: function(){
            return this._year;
        },
    set: function(newValue){
            /* original code
            if(newValue > 2004){
                this._year = newValue;
                this.edition += newValue - 2004;
            }
            */
            if(newValue > this._year){
                this._year = newValue;
                this.edition++;
            }
        }
});

book.year = 2007;

console.log(book.edition);
//2

Object.getOwnPropertyDescriptor(book, "_year");
//Object {value: 2007, writable: true, enumerable: true, configurable: true}
Object.getOwnPropertyDescriptor(book,"edition");
//Object {value: 2, writable: true, enumerable: true, configurable: true}
Object.getOwnPropertyDescriptor(book, "year");
//Object {get: function, set: function, enumerable: false, configurable: false}

/*****************************************/
// not working and NOT identical to the example above
/*  In the first example _year can be set to different value, because it was created
    using object literal notation, so its writable, enumerable and configurable attributes
    are set to true which means that it can be changed by the year get method.
    In the defineProperties example below, these attributes are set to false by default,
    so the _year and edition can't be changed and the code isn't working as expected.
*/


var book = {};
Object.defineProperties(book,{
    _year: {
        value: 2004
    },
    edition: {
        value: 1
    },

    year: {
        get: function(){
                return this._year;
            },
        set: function(newValue){
                if(newValue>this._year){
                    this._year = newValue;
                    this.edition++;
                }
            }
    }
});

book.year = 2007;
console.log(book.year); //2004
console.log(book.edition); //1

Object.getOwnPropertyDescriptor(book,"_year");
//Object {value: 2004, writable: false, enumerable: false, configurable: false}
Object.getOwnPropertyDescriptor(book,"edition");
//Object {value: 1, writable: false, enumerable: false, configurable: false}
Object.getOwnPropertyDescriptor(book,"year");
//Object {get: function, set: function, enumerable: false, configurable: false}




/*****************************************/
// working and identical to the first example

var book = {};
Object.defineProperties(book,{
    _year: {
        value: 2004,
        writable: true,
        enumerable: true,
        configurable: true
    },
    edition: {
        value: 1,
        writable: true,
        enumerable: true,
        configurable: true
    },

    year: {
        get: function(){
                return this._year;
            },
        set: function(newValue){
                if(newValue>this._year){
                    this._year = newValue;
                    this.edition++;
                }
            }
    }
});

book.year = 2007;
console.log(book.year); // 2007
console.log(book.edition); // 2
book.year = 2009;
console.log(book.edition); // 3