Skip to main content

prefer_spread_collections

Learn about the prefer_spread_collections linter rule.

Stable
Recommended
Fix available

Use spread collections when possible.

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];

Enable

#

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

If you're instead using the YAML map syntax to configure linter rules, add prefer_spread_collections: true under linter > rules:

analysis_options.yaml
yaml 
linter:  rules:  prefer_spread_collections: true

Unless stated otherwise, the documentation on this site reflects Dart 3.10.3. Report an issue.