dart - 方法 'set_age' 没有为类 'Person' 定义。在 Dart

Question

我是 dart 的新手当我尝试将值设置为变量(这是一个私有(private)变量)并且我正在使用 getters 时出现此错误和 setters
但我收到此错误:

The method 'set_age' isn't defined for the class 'Person'.

这是我的代码的样子。

class Person{
  String firstName, lastName;
  int _pAge;
  double pSalary;

//  syntactic sugar
  Person(this.firstName, this.lastName, this.pSalary);

//  Named constructor
  Person.origin(){
    firstName = "";
    lastName = "";
    _pAge = 0;
    pSalary = 0.0;
  }

  String fullName() => this.firstName + " " + this.lastName;

//  getters and setters for _pAge
  set set_age(int age){
    _pAge =  age;
  }

  int get get_age => _pAge;
}

main() {
  Person p1 = new Person("Jananath", "Banuka", 15000.00);
  Person p2 = new Person("Thilina", "Kalansooriya", 55000.00);

  p1.set_age(10); //this is where the error is coming from

  print(p1.fullName());
  print(p2.fullName());
}

Answer 1

您不是在编写惯用的 Dart，这可能就是您将 setter 视为函数的原因。 setter 是通过分配给它们来调用的，所以而不是 p1.set_age(10)它应该只是 p1.age = 10; .

你的代码，作为惯用的 Dart，看起来像:

class Person{
  String firstName, lastName;
  int age;
  double salary;

  Person(this.firstName, this.lastName, this.salary) : age = 0;

  Person.origin() 
    : firstName = "", lastName = "", age = 0, salary = 0; 

  String get fullName => "$firstName $lastName";
}

main() {
  Person p1 = new Person("Jananath", "Banuka", 15000.00);
  Person p2 = new Person("Thilina", "Kalansooriya", 55000.00);

  p1.age = 10;

  print(p1.fullName);
  print(p2.fullName);
}

这使得 age一个公共(public)领域。无需在公共(public) setter/getter 后面隐藏私有(private)字段，然后将其转发到该字段。您可以直接公开该字段。

Dart 具有 setter 和 getter 正是因为这样就不会阻止您将来向 set/get 操作添加逻辑。你可以随时改变

int age;

到

int _age;
int get age => _age;
set age(int value) {
  log("SETTING AGE: $value");
  _age = value;
}

如果需要，请稍后再做。