dart - extends Object with Observable 和 extends Observable 有什么区别

Question

使用 Observable 扩展 Object 和应用于以下类的扩展 Observable 之间有什么区别。

当应用程序运行时，结果是一样的。

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;
  }
}

Answer 1

这两个声明之间的行为没有区别。

这是a quote from Florian Loitsch :

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( superclass 不一样):

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'
}