运算符“=”在 Dart 的类声明中是什么意思？

Question

In my studies of Dart languages, I found some packaged using this kind of class declaration:在我对 Dart 语言的研究中，我发现了一些使用这种类声明的封装：


class _Base = Authentication with Utilities, Validators;

I don't understand what the operator = is doing here, is it a kind of alias?我不明白运算符=在这里做什么，它是一种别名吗？

Answer 1

Is a shortcut to create inherit classes with mixins.是使用 mixins 创建继承类的快捷方式。

The example is same to:该示例与以下内容相同：

class _Base extends Authentication with Utilities, Validators{
  _Base(): super(); // or with args
}

Utilities and validators are mixins.实用程序和验证器是 mixin。