avoid-slow-collection-methods

added in: 1.15.0

performance

Warns when an invocation is a slow sync* invocation.

Using sync* invocations can result in a ~2 times slower code compared to other approaches.

Additionally, this rule highlights .expand() usages as replacing them with a spread gives ~3 times performance difference. See the second link for more details.

Additional resources:

• https://github.com/dart-lang/sdk/issues/51806
• https://github.com/dart-lang/sdk/blob/main/pkg/analyzer/lib/src/utilities/extensions/collection.dart#L37

Example

❌ Bad:

void fn() {
  const iterable = [null, 2, 3, 4, 5, 6, 7, 8, 9];

  iterable.whereNotNull(); // LINT
}

✅ Good:

void fn() {
  const iterable = [null, 2, 3, 4, 5, 6, 7, 8, 9];

  iterable.whereType<int>();
}