Redeclare "==" operator inside an extension type - Dart

Question

I cannot redeclare the "==" operator inside an extension type

extension type Compare(List<int> types) {
   @redeclare
    bool operator ==(List<int> other)  =>true;
}

I get these errors:

Extension types can't declare members with the same name as a member declared by 'Object'. Try specifying a different name for the member

and this

The method doesn't redeclare a method declared in a superinterface. Try updating this member to match a declaration in a superinterface, or removing the redeclare annotation

Is there a way to redeclare it inside an extension type?

Answer 1

Extensions can't declare members with the same name as a member declared by 'Object'.

The analyzer produces this diagnostic when an extension declaration declares a member with the same name as a member declared in the class Object. Such a member can never be used because the member in Object is always found first.

Example:

The following code produces this diagnostic because toString is defined by Object:

extension E on String {
  String toString() => this;
}

Since members of the Object class can't be overridden in an extension, you should use another name for your desired functionality.

extension ListComparison on List<int>{

  bool equals (List<int> other){
    if(length != other.length)
      return false;
    for(int i = 0 ; i < length; i++){

      if(this[i] != other[i])
        return false;
    }

    return true;
  }
  
  // you can't overload == operator in extensions, reserved by object

}

  print([1,2,3].equals([1,2,3])); // true
  print([1,2,3].equals([1,2,2])); // false

Hope it helps you.