Contents

exhaustive_cases

Contents

Define case clauses for all constants in enum-like classes.

This rule is available as of Dart 2.9.

Rule sets: recommended, flutter

This rule has a quick fix available.

Details

#

Switching on instances of enum-like classes should be exhaustive.

Enum-like classes are defined as concrete (non-abstract) classes that have:

  • only private non-factory constructors
  • two or more static const fields whose type is the enclosing class and
  • no subclasses of the class in the defining library

DO define case clauses for all constants in enum-like classes.

BAD:

dart
class EnumLike {
  final int i;
  const EnumLike._(this.i);

  static const e = EnumLike._(1);
  static const f = EnumLike._(2);
  static const g = EnumLike._(3);
}

void bad(EnumLike e) {
  // Missing case.
  switch(e) { // LINT
    case EnumLike.e :
      print('e');
      break;
    case EnumLike.f :
      print('f');
      break;
  }
}

GOOD:

dart
class EnumLike {
  final int i;
  const EnumLike._(this.i);

  static const e = EnumLike._(1);
  static const f = EnumLike._(2);
  static const g = EnumLike._(3);
}

void ok(EnumLike e) {
  // All cases covered.
  switch(e) { // OK
    case EnumLike.e :
      print('e');
      break;
    case EnumLike.f :
      print('f');
      break;
    case EnumLike.g :
      print('g');
      break;
  }
}

Usage

#

To enable the exhaustive_cases rule, add exhaustive_cases under linter > rules in your analysis_options.yaml file:

analysis_options.yaml
yaml
linter:
  rules:
    - exhaustive_cases

Unless stated otherwise, the documentation on this site reflects Dart 3.6.0. Page last updated on 2024-07-03. View source or report an issue.