Assigning an object to another hold a reference of the assigned Object. Why is this if Dart is Assigned by Value

Question

I have a simple programme in dart to test out if variables assigned hold reference.

 class User{
  int? id;
  String? name;
  int? age;

  User(this.id, this.name, this.age);
}



  User user1 = User(1,'Harry', 21);
  User user2 = user1;
  user2.name =  'James';

  print(user1.name); //prints out James
  print(user2.name); //prints out James

I read that Dart is an Assigned by value language. So why does user1.name have a value of James and not Harry even if it was not explicitly changed?.

Does this answer your question? https://stackoverflow.com/q/25170094/ — jamesdlin, Sep 16 '21 at 10:27

score 2 · Answer 1 · answered Sep 16 '21 at 10:30

Dart is an object oriented language, and like almost every other object oriented language, objects have identity.

That means objects are not denotable values, though; you can't store an object in a variable because the object has an existence, an identity, independent of that variable. You can only store a reference to an object in the variable.

Dart is call-by-value, but all the values are object references.

It's the same in Java, JavaScript and Python. C# has non-object values too, but for its objects, aka. "reference types", it works exactly the same. Dart does not have any values which are not objects.

Assigning an object to another hold a reference of the assigned Object. Why is this if Dart is Assigned by Value

1 Answers1