Skip to main content

avoid-duplicate-cascades

added in: 1.11.0
warning
⚙️🛠
Pro+
preset: recommended

Warns when a cascade expression has duplicate cascades.

Duplicate cascades are usually the result of a typo and a sign of a bug.

⚙️ Config​

Set ignored-types (default is empty) to allow duplicate cascades on the variables of the configured type (example).

analysis_options.yaml
dart_code_metrics:
  rules:
    - avoid-duplicate-cascades:
        ignored-types:
          - BuildContext

Example​

❌ Bad:

void fn() {
  final value = SomeClass();

  value
    ..field = '2' // LINT: Avoid duplicate cascades. Try removing the duplicate cascade expression or replacing it with a different expression.
    ..field = '1' // LINT: Avoid duplicate cascades. Try removing the duplicate cascade expression or replacing it with a different expression.
    ..field = '1' // LINT: Avoid duplicate cascades. Try removing the duplicate cascade expression or replacing it with a different expression.
    ..another = '1';

  value
    ..method(() => 1) // LINT: Avoid duplicate cascades. Try removing the duplicate cascade expression or replacing it with a different expression.
    ..method(() => 1) // LINT: Avoid duplicate cascades. Try removing the duplicate cascade expression or replacing it with a different expression.
    ..method(() => 2);

  final list = [1, 2, 3];

  list
    ..[1] = 2 // LINT: Avoid duplicate cascades. Try removing the duplicate cascade expression or replacing it with a different expression.
    ..[1] = 2 // LINT: Avoid duplicate cascades. Try removing the duplicate cascade expression or replacing it with a different expression.
    ..[1] = 3 // LINT: Avoid duplicate cascades. Try removing the duplicate cascade expression or replacing it with a different expression.
    ..[2] = 2;
}

class SomeClass {
  String? field;
  String? another;

  void method(Function callback) {}
}

✅ Good:

void fn() {
  final value = SomeClass();

  value
    ..field = '2'
    ..another = '1'; // Correct, different target fields

  value
    ..method(() => 1)
    ..method(() => 2); // Correct, different callbacks

  final list = [1, 2, 3];

  list
    ..[1] = 2;
    ..[2] = 3; // Correct, different target indexes
}

class SomeClass {
  String? field;
  String? another;

  void method(Function callback) {}
}

Example with "ignored-types"​

Config
analysis_options.yaml
dart_code_metrics:
  rules:
    - avoid-duplicate-cascades:
        ignored-types:
          - BuildContext

✅ Good:

void someFunction(BuildContext context) {
  // Correct, BuildContext is ignored
  context
    ..pop()
    ..pop();
}

Additional Resources​