具有Observable的extends对象和具有Observable的extends有什么区别 [英] What is the difference between extends Object with Observable and extends Observable

问题描述

具有Observable的extended Object和应用于以下类的extended Observable之间有什么区别。

What is the difference between extends Object with Observable and extends Observable as applied to the class below.

运行应用程序时，结果是相同的。

The result is the same when the application is run.

library models;

import 'package:polymer/polymer.dart';

class Person extends Object with Observable {
  @observable String name;
  @observable bool signedAgreement = false;

  Person();

  Person.from(Person other) {
    name = other.name;
    signedAgreement = other.signedAgreement;
  }

  blank() {
    name = '';
    signedAgreement = false;
  }
}


library models;

import 'package:polymer/polymer.dart';

class Person extends Observable {
  @observable String name;
  @observable bool signedAgreement = false;

  Person();

  Person.from(Person other) {
    name = other.name;
    signedAgreement = other.signedAgreement;
  }

  blank() {
    name = '';
    signedAgreement = false;
  }
}

推荐答案

有这两个声明之间的行为没有区别。

There no difference in the behaviour between this two declarations.

这里是来自Florian Loitsch的引用：

当您扩展对象使用混合器时，第一个混合器总是可以代替对象。

When you extend "Object" with a mixin the first mixin can always take the place of "Object".

唯一的区别在于类层次结构（超类不一样）：

The only little difference is in class hierarchy (superclass are not the same) :

import 'dart:mirrors';

abstract class Mixin {}
class A extends Mixin {}
class B extends Object with Mixin {}

main() {
  print(reflectClass(A).superclass); 
  // => ClassMirror on 'Mixin'

  print(reflectClass(A).superclass.superclass);
  // => ClassMirror on 'Object'

  print(reflectClass(B).superclass); 
  // => ClassMirror on 'dart.core.Object with .Mixin'

  print(reflectClass(B).superclass.superclass); 
  // => ClassMirror on 'Object'
}

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