Contents
description bug_report

prefer_spread_collections

Contents

Use spread collections when possible.

This rule is available as of Dart 2.3.0.

Rule sets: recommended, flutter

This rule has a quick fix available.

Details

#

Use spread collections when possible.

Collection literals are excellent when you want to create a new collection out of individual items. But, when existing items are already stored in another collection, spread collection syntax leads to simpler code.

BAD:

dart
Widget build(BuildContext context) {
  return CupertinoPageScaffold(
    child: ListView(
      children: [
        Tab2Header(),
      ]..addAll(buildTab2Conversation()),
    ),
  );
}
dart
var ints = [1, 2, 3];
print(['a']..addAll(ints.map((i) => i.toString()))..addAll(['c']));
dart
var things;
var l = ['a']..addAll(things ?? const []);

GOOD:

dart
Widget build(BuildContext context) {
  return CupertinoPageScaffold(
    child: ListView(
      children: [
        Tab2Header(),
        ...buildTab2Conversation(),
      ],
    ),
  );
}
dart
var ints = [1, 2, 3];
print(['a', ...ints.map((i) => i.toString()), 'c');
dart
var things;
var l = ['a', ...?things];

Usage

#

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

analysis_options.yaml
yaml
linter:
  rules:
    - prefer_spread_collections