dart - 构造函数中的语法错误

Question

以下代码

class MemberException extends ServerException {
  String message;
  MemberException(message) {
    super(message);
  }
}

class ServerException implements Exception {
  String message;
  ServerException(this.message);
}

产生以下(有点无用)错误消息

Too few arguments in implicit super() constructor invocation in '(String) -> dynamic'

Answer 1

正确的格式是:

class MemberException extends ServerException {
  String message;
  MemberException(message) : super(message) {
    // constructor body
  }
}

您需要在调用构造函数主体之前初始化super。
引用: http://www.dartlang.org/docs/dart-up-and-running/contents/ch02.html#ch02-constructors(请参阅初始化器部分)