wrapMain function

void wrapMain(FutureOr<void> callback(), { bool chainStackTraces = true, bool? printScriptException, bool verboseTrace = false, bool debug = false, })

A wrapper for the body of the top-level main() method.

It's recommended that all scripts wrap their main() methods in this function. It gracefully exits when an error is unhandled, and (if chainStackTraces is true) tracks stack traces across asynchronous calls to produce better error stacks.

By default, if a Script fails in callback, this just exits with that script's exit code without printing any additional error messages. If printScriptException is true (or if it's unset and debug is true), this will print the exception and its stack trace to stderr before exiting.

By default, stack frames from the Dart core libraries and from this package will be folded together to make stack traces more readable. If verboseTrace is true, the full stack traces will be printed instead.

If debug is true, extra information about Scripts' lifecycles will be printed directly to stderr. As the name suggests, this is intended for use only when debugging.

Implementation

void wrapMain(FutureOr<void> callback(),
    {bool chainStackTraces = true,
    bool? printScriptException,
    bool verboseTrace = false,
    bool debug = false}) {
  withConfig(() {
    Chain.capture(callback, onError: (error, chain) {
      if (error is! ScriptException) {
        stderr.writeln(error);
        stderr.writeln(terseChain(chain));
        // Use the same exit code that Dart does for unhandled exceptions.
        exit(254);
      }

      if (printScriptException ?? debug) {
        stderr.writeln(error);
        stderr.writeln(terseChain(chain));
      }
      exit(error.exitCode);
    }, when: chainStackTraces);
  }, verboseTrace: verboseTrace, debug: debug);
}