spawnUri static method

Future<Isolate> spawnUri(
  1. Uri uri,
  2. List<String> args,
  3. dynamic message, {
  4. bool paused = false,
  5. SendPort? onExit,
  6. SendPort? onError,
  7. bool errorsAreFatal = true,
  8. bool? checked,
  9. Map<String, String>? environment,
  10. @Deprecated('The packages/ dir is not supported in Dart 2') Uri? packageRoot,
  11. Uri? packageConfig,
  12. bool automaticPackageResolution = false,
  13. @Since("2.3") String? debugName,
})

Spawns an isolate running the script file specified by uri.

Creates and spawns a new isolate that runs the Dart program which has the uri file as the entry point that provides the main method. The new isolate belongs to a new isolate group, different from the isolate group of the spawning isolate.

The isolate starts executing the top-level main function of the library with the given URI.

The target main must be callable with zero, one or two arguments. Examples:

  • main()
  • main(args)
  • main(args, message)

When present, the parameter args is set to the provided args list. When present, the parameter message is set to the initial message. A runtime error occurs if the message argument's runtime type cannot be assigned to the second parameter of the main method.

If the paused parameter is set to true, the isolate will start up in a paused state, as if by an initial call of isolate.pause(isolate.pauseCapability). To resume the isolate, call isolate.resume(isolate.pauseCapability).

If the errorsAreFatal, onExit and/or onError parameters are provided, the isolate will act as if, respectively, setErrorsFatal, addOnExitListener and addErrorListener were called with the corresponding parameter and was processed before the isolate starts running.

You can also call the setErrorsFatal, addOnExitListener and addErrorListener methods on the returned isolate, but unless the isolate was started as paused, it may already have terminated before those methods can complete.

The checked parameter controls whether asserts are enabled in the created isolate. In a production-mode program, the parameter is ignored, and assertions are always disabled in all isolates. Otherwise if a true or false value is provided, assertions are enabled or disabled, respectively, in the created isolate. If null or no argument is provided, asserts are enabled in the created isolate if and only if they are enabled in the spawning isolate.

It may not always be possible to honor the checked parameter. If the isolate code was pre-compiled, it may not be possible to change the checked mode setting dynamically. In that case, the checked parameter is ignored.

If the packageConfig parameter is provided, then it is used to find the location of a package resolution configuration file for the spawned isolate.

If the automaticPackageResolution parameter is provided, then the location of the package sources in the spawned isolate is automatically determined.

The environment is a mapping from strings to strings which the spawned isolate uses when looking up String.fromEnvironment values. The system may add its own entries to environment as well. If environment is omitted, the spawned isolate has the same environment declarations as the spawning isolate.

WARNING: The environment parameter is not implemented on all platforms yet.

If debugName is provided, the spawned Isolate will be identifiable by this name in debuggers and logging.

Returns a future that will complete with an Isolate instance if the spawning succeeded. It will complete with an error otherwise.

Implementation

external static Future<Isolate> spawnUri(
    Uri uri, List<String> args, var message,
    {bool paused = false,
    SendPort? onExit,
    SendPort? onError,
    bool errorsAreFatal = true,
    bool? checked,
    Map<String, String>? environment,
    @Deprecated('The packages/ dir is not supported in Dart 2')
    Uri? packageRoot,
    Uri? packageConfig,
    bool automaticPackageResolution = false,
    @Since("2.3") String? debugName});