better_require_trailing_commas 2.5.1

A lint rule that enforces trailing commas behaves like ESLint’s comma-dangle with the always-multiline option.

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.

Rules

All rules are enabled by default. You can disable each rule in analysis_options.yaml (see Installation section).

better_require_trailing_commas

Enforces trailing commas for multiline collections, function calls, function definitions, and other constructs that support trailing commas.

✅ 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;
}

avoid_unnecessary_commas

Disallows unnecessary trailing commas for single-line collections, function calls, function definitions, and other constructs that support trailing commas.

✅ Good

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

❌️ Bad

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

Installation

Dart 3.10 or later (Flutter 3.38 or later) is required to use this plugin.

Edit your analysis_options.yaml like below. You don't need to add this to your dependencies in pubspec (for more information, see here).

Normal Usage

By specifying ^2.3.0, the version will be automatically resolved to an appropriate one depending on your other plugins and Dart version.

# ...
# Note: `plugins` is the TOP level key.
plugins:
  better_require_trailing_commas: ^2.3.0
# ...

Using with riverpod_lint

Please put riverpod_lint plugin before better_require_trailing_commas plugin. Otherwise, unexpected behavior may occur.

# ...
plugins:
  riverpod_lint: ^3.1.3 # Put this BEFORE better_require_trailing_commas
  better_require_trailing_commas: ^2.3.0

Disable Each Rule

Each rule can be disabled by diagnostics section like below:

plugins:
  better_require_trailing_commas:
    version: ^2.2.0
    diagnostics:
      avoid_unnecessary_commas: false

Usage

Running the linter with command line:

dart analyze