In Dart, how to access a parent private var from a subclass in another file?

Question

I have two classes in Dart, MyClass1 and MyClass2 where MyClass2 extends MyClass1. In some of MyClass2 functions, I want to access a variable that has "private" access privileges in MyClass1. If MyClass1 and MyClass2 are declared in the same dart file, like this:

class MyClass1 {
  double _myprivatevar;
}

class MyClass2 extends MyClass1 {

  MyClass2(double myvar){
    this._myprivatevar = myvar;
  }
}  

everything is fine But now, if MyClass2 is declared in its own dart file:

import 'package:test/myclass1.dart';

class MyClass2 extends MyClass1 {

  MyClass2 (double myvar){
    this._myprivatevar = myvar;
  }
}

I have an error saying:

The setter '_myprivatevar' isn't defined for the class 'MyClass2'. Try importing the library that defines '_myprivatevar', correcting the name to the name of an existing setter, or defining a setter or field named '_myprivatevar'.dart(undefined_setter)

how can I solve this issue and have access to a parent private variable from a subclass defined in another dart file?

Answer 1

You can use @protected annotation for this.

class MyClass1 {
  double _myprivatevar;

  @protected double get myprivatevar => _myprivatevar;

  @protected set myprivatevar(newValue) {
    _myprivatevar = newValue;
  }
    
}

class MyClass2 extends MyClass1 {

  MyClass2(double myvar){
    myprivatevar = myvar;
  }
}  

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