Chapter 6.2 Constructor specify argument type

📚 Official Books Dart Apprentice
1

Take this as an example:

class User {
  User({int id = 0, String name = 'anonymous'})
      : _id = id,
        _name = name;

  int _id;
  String _name;
}

I find that there is no error if I remove the argument type in the constructor:

class User {
  User({id = 0, name = 'anonymous'})
      : _id = id,
        _name = name;

  int _id;
  String _name;
}

Is there any difference between the two? When do we need to specify the argument type in the constructor?

2

No difference. In the second one Dart is just inferring the type from the initializing value (0 and ‘anonymous’ already have a type).

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3

Thank you. I think that the second is a more neat way to present the constructor.

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