我应该如何在Dart中使用assert？

由未命名发布于 2020-05-09 14:29:31

我看到了类似以下示例代码：

class ModelBinding extends StatefulWidget {
  ModelBinding({
    Key key,
    this.initialModel = const GalleryOptions(),
    this.child,
  })  : assert(initialModel != null),
        super(key: key);
...

所以我写了一些东西：

class Person {
  String firstName;

  Person({name}){
   print(name);
  }
}

class Employee extends Person {
  Employee(String name) : assert(false), super(name: name);
}

main() {
  var emp = new Employee('Jason');
}

无论assert（false）或assert（true），结果都是相同的。

那么assert的含义是什么

谢谢

wodio

2020-05-09 14:29:31

assert is used for debugging and it simply means the condition should be true to proceed. Let me explain:

class MyClass {
  final int age;

  MyClass({this.age});

  void someMethod() {
    // using `age` here
  }
}

You might face issues in someMethod if age passed is null, so to make sure it isn't null, you use assert like:

class MyClass {
  final int age;

  MyClass({this.age}) : assert(age != null, "Make sure age isn't null");

  void someMethod() {
    // using `age` here
  }
}

未命名

这家伙很懒，什么都没留下

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