better_require_trailing_commas #

Dart linter plugin to enforce trailing commas (enhanced version of linter built-in require_trailing_commas)

The rule is simple. If you opened parentheses intending to write multiline contents, it requires trailing commas. It's like always-multilinesetting of comma-dangle rule in ESLint.

✅ Good #

Foo(
  a: 1,
  b: 2,
);

Foo(Bar(
  a: 1,
  b: 2,
));

useEffect(() {
  // ...
}, []);

❌️ Bad #

Foo(
  a: 1,
  b: 2 // <-
);

Foo(Bar(
  a: 1,
  b: 2 // <-
));

useEffect(
  () {
    // ...
  },
  [] // <-
);

Records are supported

final (String, String) foo = (
  "bar",
  "baz" // <-
);

Switch expressions are supported

final foo = switch (state) {
  State.success => 0,
  State.failure => 1 // <-
}

Enums are supported

enum FooState {
  bar,
  baz // <-
}

enum BarState {
  taro("taro"),
  hanako("hanako") // <-
  ;
  
  const BarState(this.name);

  final String name;
}

Of course, also have quick fixes.

Installation #

Just add this package to your dependencies. This plugin requires Dart SDK >= 3.10 or Flutter SDK >= 3.38.

dart pub add dev:better_require_trailing_commas
# or
flutter pub add dev:better_require_trailing_commas

If you're using an IDE like VSCode, edit your analysis_options.yaml like this:

# ...
# Note: `plugins` property is TOP LEVEL.
plugins:
  better_require_trailing_commas:
    version: ^2.0.0
    diagnostics:
      better_require_trailing_commas: true
# ...

Running the linter with command line:

dart analyze