>=2.12.0-0 <3.0.0
based on beta release guidelines.2.12
sdk.@internal
to annotate elements that should not be used outside of the package in which the element is declared.unawaited
because the attempt to move it from package:pedantic
caused too many issues. If you see errors about unawaited
being declared in two places, please update the version constraints for meta
to 1.2.2
or later.unawaited
to mark invocations that return a Future
where it's intentional that the future is not being awaited. (Moved from package:pedantic
.)@doNotStore
to annotate methods, getters and functions to indicate that values obtained by invoking them should not be stored in a field or top-level variable.@nonVirtual
to annotate instance members that should not be overridden in subclasses or when mixed in.Introduce @sealed
to declare that a class or mixin is not allowed as a super-type.
Only classes in the same package as a class or mixin annotated with @sealed
may extend, implement or mix-in the annotated class or mixin. (SDK issue 27372).
Introduce @alwaysThrows
to declare that a function always throws (SDK issue 17999). This is first available in Dart SDK 1.25.0-dev.1.0.
import 'package:meta/meta.dart'; // Without knowing that [failBigTime] always throws, it looks like this // function might return without returning a bool. bool fn(expected, actual) { if (expected != actual) failBigTime(expected, actual); else return True; } @alwaysThrows void failBigTime(expected, actual) { throw new StateError('Expected $expected, but was $actual.'); }
@experimental
to annotate a library, or any declaration that is part of the public interface of a library (such as top-level members, class members, and function parameters) to indicate that the annotated API is experimental and may be removed or changed at any-time without updating the version of the containing package, despite the fact that it would otherwise be a breaking change.Introduce @virtual
to allow field overrides in strong mode (SDK issue 27384).
import 'package:meta/meta.dart' show virtual; class Base { @virtual int x; } class Derived extends Base { int x; // Expose the hidden storage slot: int get superX => super.x; set superX(int v) { super.x = v; } }
Introduce @checked
to override a method and tighten a parameter type (SDK issue 25578).
import 'package:meta/meta.dart' show checked; class View { addChild(View v) {} } class MyView extends View { // this override is legal, it will check at runtime if we actually // got a MyView. addChild(@checked MyView v) {} } main() { dynamic mv = new MyView(); mv.addChild(new View()); // runtime error }
@visibleForTesting
annotation for declarations that may be referenced only in the library or in a test.@factory
to allow statics and methods returning null
.@protected
to include implemented interfaces (linter#252).@optionalTypeArgs
annotation for classes whose type arguments are to be treated as optional.Required
constructor with a means to specify a reason to explain why a parameter is required.@factory
annotation for methods that must either be abstract or must return a newly allocated object.@literal
annotation that indicates that any invocation of a constructor must use the keyword const
unless one or more of the arguments to the constructor is not a compile-time constant.@protected
annotation for members that must only be called from instance members of subclasses.@required
annotation for optional parameters that should be treated as required.@mustCallSuper
annotation for methods that must be invoked by all overriding methods.