CODEWITHSUNDEEP
dart
Rezney
Rezney

Reputation: 371

Does Dart have a concept of class variables?

While going through A Tour of the Dart Language I see this example in the Constructors section:

class Point {
  num x, y;

  Point(num x, num y) {
    // There's a better way to do this, stay tuned.
    this.x = x;
    this.y = y;
  }
}

Talking about instances variables. Coming from Python this initially confused me a little as I though num x, y; would be kind of class variables.

Does Dart have a concept of class variables?

Upvotes: 3

Views: 5884

Answers (1)

Günter Zöchbauer
Günter Zöchbauer

Reputation: 657168

Not sure what you mean by "class variables".
I assume you mean static variables.

Static variables exist once per class, while instance variables exist once per instance.

class Point {
  static num x, y;

  fooMethod() {
    print('$x, $y');
  }
}

With in the class where they are declared, they can be accessed without a prefix. From everywhere else they are accessed using the lass name as prefix where they are declared.

void main() {
  print(Point.x);
}

Also from subclasses the class prefix where the fields are declared are required because they are not inherited.

class CustomPoint extends Point {

  barMethod() {
    print('${Point.x}, ${Point.y}');
  }
}

Upvotes: 6

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