A small script to compare dart's "foo is T" and "runtimeType" type checks

dart_types.dart

Type type<T>() => T;

class Settings {
  // logic here ...
}

class ASettings extends Settings {
  // logic here ...
}

class BSettings extends ASettings {
  // logic here ...
}

var _settings = Settings();
var _aSettings = ASettings();
var _bSettings = BSettings();

void main() {
  print('using "foo is T":\n');
  fooIsT();
  print('\n\nusing "runtimeType == Type":\n');
  objectRuntimeType();
}

void fooIsT() {
  print('$Settings is $ASettings => ${_settings is ASettings}');
  print('$ASettings is $Settings => ${_aSettings is Settings}');
  print('$Settings is $BSettings => ${_settings is BSettings}');
  print('$BSettings is $Settings => ${_bSettings is Settings}');
  print('$ASettings is $BSettings => ${_aSettings is BSettings}');
  print('$BSettings is $ASettings => ${_bSettings is ASettings}');
}

void objectRuntimeType() {
  print('$Settings == $ASettings => ${_settings.runtimeType == type<ASettings>()}');
  print('$ASettings == $Settings => ${_aSettings.runtimeType == type<Settings>()}');
  print('$Settings == $BSettings => ${_settings.runtimeType == type<BSettings>()}');
  print('$BSettings == $Settings => ${_bSettings.runtimeType == type<Settings>()}');
  print('$ASettings == $BSettings => ${_aSettings.runtimeType == type<BSettings>()}');
  print('$BSettings == $ASettings => ${_bSettings.runtimeType == type<ASettings>()}');
  print('\ncorrect types:\n');
  print('$Settings == $Settings => ${_settings.runtimeType == type<Settings>()}');
  print('$ASettings == $ASettings => ${_aSettings.runtimeType == type<ASettings>()}');
  print('$BSettings == $BSettings => ${_bSettings.runtimeType == type<BSettings>()}');
}

using "foo is T":

Settings is ASettings => false
ASettings is Settings => true
Settings is BSettings => false
BSettings is Settings => true
ASettings is BSettings => false
BSettings is ASettings => true

using "runtimeType == Type":

Settings == ASettings => false
ASettings == Settings => false
Settings == BSettings => false
BSettings == Settings => false
ASettings == BSettings => false
BSettings == ASettings => false

correct types:

Settings == Settings => true
ASettings == ASettings => true
BSettings == BSettings => true