24

ember.js 的reopenClass 的功能我是不太懂。我认为它向对象的原型添加了额外的代码，因此该对象的所有实例都将获得以非静态方式添加的功能。然而，它并没有这样做。看起来它只添加了可以静态执行的代码。例如。我有这个代码：

Logger = Ember.Object.extend({ 
  log: function(thing) { 
     console.log(thing + ' wassup'); 
    }
});

var logger = Logger.create();
logger.log("1, yo")

logger.reopen({ 
  log: function(name) { 
      console.log(name + 'ghurt')
    }
});
logger.log("2, yo")

Logger.reopenClass({ 
  log: function(name) { 
      console.log(name + 'fresh')
    }
});
logger.log("3, yo")
Logger.log("4, yo")

它输出这个：

1, yo wassup
2, yoghurt
3, yoghurt
4, yofresh

我的预期是这样的：

1, yo wassup
2, yoghurt
3, yofresh
4, undefined (I think)

所以我的问题是：reopenClass 做什么以及何时使用它？

4

2 回答 2

45

通常，reopen将方法和属性添加到实例，而reopenClass将方法和属性添加到类。

对应的测试是ember-runtime/tests/system/object/reopen_test.js和packages/ember-runtime/tests/system/object/reopenClass_test.js。

我已经更新了您的代码并添加了一些评论，请参阅http://jsfiddle.net/pangratz666/yWKBF/：

Logger = Ember.Object.extend({
    log: function(thing) {
        console.log(thing + ' wassup');
    }
});

var logger1 = Logger.create();
var logger2 = Logger.create();

// instances of Logger have a 'wassup' method
try { Logger.log("1, yo"); } catch (e) {} // Object (subclass of Ember.Object) has no method 'log'
logger1.log("1, yo"); // 1, yo wassup
logger2.log("1, yo"); // 1, yo wassup

console.log('----');

// overwrite log of concrete logger instance logger1
logger1.reopen({
    log: function(name) {
        console.log(name + ' ghurt');
    }
});

try { Logger.log("1, yo"); } catch (e) {} // Object (subclass of Ember.Object) has no method 'log'
logger1.log("2, yo"); // 2, yo ghurt
logger2.log("2, yo"); // 2, yo wassup

console.log('----');

// classes of Logger have a 'fresh' method
Logger.reopenClass({
    log: function(name) {
        console.log(name + ' fresh');
    }
});

Logger.log("3, yo"); // 3, yo fresh
logger1.log("3, yo"); // 3, yo ghurt
logger2.log("3, yo"); // 3, yo wassup

console.log('----');

// new* instances of Logger have from now on a 'dawg' method
// * this will likely change in the future so already existing instances will reopened too
Logger.reopen({
    log: function(name) {
        console.log(name + ' dawg');
    }
});

Logger.log("4, yo"); // 4, yo fresh
logger1.log("4, yo"); // 4, yo ghurt
logger2.log("4, yo"); // 4, yo wassup
Logger.create().log("4, yo"); // 4, yo dawg

console.log('----');

​</p>

于 2012-04-22T18:12:47.903 回答
0

reopen更改原型，从而更改类的实例

reopenClass更改构造函数本身，从而 通过创建仅在类上可用但在类的任何实例上不可用的静态属性和函数来更改类。

请注意，由 引入的更改reopen仅在调用后生效.create()

基于文档的代码示例：

http://emberjs.com/api/classes/Ember.Application.html#method_reopen

MyObject = Ember.Object.extend({
  name: 'an object'
});

o = MyObject.create();
o.get('name'); // 'an object'

MyObject.reopen({
  say: function(msg){
    console.log(msg);
  }
})

try{
    o.say("hey");
} catch(e) {
    console.log(e); // o.say is not a function (...yet)
}
o2 = MyObject.create();
o2.say("hello"); // logs "hello"

o.say("goodbye"); // logs "goodbye"

http://emberjs.com/api/classes/Ember.Application.html#method_reopenClass

MyObject = Ember.Object.extend({
  name: 'an object'
});

MyObject.reopenClass({
  canBuild: false
});

MyObject.canBuild; // false
o = MyObject.create();
o.canBuild; // undefined
于 2015-04-20T03:50:50.410 回答