throwable

Checked exceptions for Dart. Declare which exceptions your functions can throw and get static analysis warnings when they aren't handled.

Packages

Package	Description
throwable	Annotation for declaring thrown exception types
throwable_lints	Lint rules that enforce exception handling

Quick Start

Add throwable to your pubspec.yaml:

dependencies:
  throwable: ^1.0.0-alpha.2

Enable the plugin in your analysis_options.yaml:

plugins:
  throwable_lints:
    path: path/to/throwable_lints
    diagnostics:
      unhandled_exception_call: true # warning/error
      unhandled_throw_in_body: true # warning/error

Annotate functions with @Throws to declare their exceptions:

import 'package:throwable/throwable.dart';

@Throws([NetworkException])
Future<String> fetchData(String url) async {
  // ...
}

Callers must then handle or propagate the declared exceptions:

// OK: handled
void main() {
  try {
    fetchData('https://example.com');
  } on NetworkException catch (_) {
    // handle error
  }
}

// OK: propagated
@Throws([NetworkException])
void main() {
  fetchData('https://example.com');
}

// LINT: NetworkException not handled
void main() {
  fetchData('https://example.com');
}

Lint Rules

• unhandled_throw_in_body - Reports throw/rethrow expressions not caught locally or declared via @Throws
• unhandled_exception_call - Reports calls to @Throws-annotated functions where exceptions aren't handled or propagated