Dart hashmap memoization

main.dart

import 'dart:collection';

HashMap memoizedTextThemes = HashMap<String, String>();

abstract class PacificDesignSystem {

  String get colorScheme;
  String get textTheme {
    if(memoizedTextThemes[colorScheme] == null){
      memoizedTextThemes[colorScheme] = 'textTheme for $colorScheme';
      print('added memoized entry for $colorScheme');
    }
    return memoizedTextThemes[colorScheme];
  }
}

class PacificLight extends PacificDesignSystem {
  @override
  String get colorScheme => "light";
}

class PacificDark extends PacificDesignSystem {
  @override
  String get colorScheme => "dark";
}


void main() {
  final pLight1 = PacificLight();
  final pLight2 = PacificLight();
  final pDark1 = PacificDark();
  final pDark2 = PacificDark();
  
  print(pLight1.textTheme);
  print(pLight1.textTheme);
  print(pLight2.textTheme);
  print(pLight2.textTheme);
  
  print(pDark1.textTheme);
  print(pDark1.textTheme);
  print(pDark2.textTheme);
  print(pDark2.textTheme);
}