Add "deprecated" to the standard library.

sdk/lib/core/annotations.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of dart.core;
+
+/**
+ * The annotation "@Deprecated('expires when')" marks a feature as deprecated.
+ *
+ * The annotation "@deprecated" is a shorthand for deprecating until
+ * to an unspecified "next release".
+ *
+ * The intent of the "@Deprecated" annotation is to inform users of a feature
+ * that they should change their code, even if it is currently still working
+ * correctly.
+ *
+ * A deprecated feature is scheduled to be removed at a later time, possibly
+ * specified as the "expires" field of the annotation.
+ * This means that a deprecated feature should not be used, or code using it
+ * will break at some point in the future. If there is code using the feature,
+ * that code should be rewritten to not use the deprecated feature.
+ *
+ * A deprecated feature should document how the same effect can be achieved,
+ * so the programmer knows how to rewrite the code.
+ *
+ * The "@Deprecated" annotation applies to libraries, top-level declarations
+ * (variables, getters, setters, functions, classes and typedefs),
+ * class-level declarations (variables, getters, setters, methods, operators or
+ * constructors, whether static or not), named optional arguments and
+ * trailing optional positional parameters.
+ *
+ * Deprecation is transitive:
+ *
+ *  - If a library is deprecated, so is every member of it.
+ *  - If a class is deprecated, so is every member of it.
+ *  - If a variable is deprecated, so are its implicit getter and setter.
+ *
+ *
+ * A tool that processes Dart source code may report when:
+ *
+ * - the code imports a deprecated library.
+ * - the code exports a deprecated library, or any deprecated member of
+ *   a non-deprecated library.
+ * - the code refers statically to a deprecated declaration.
+ * - the code dynamically uses a member of an object with a statically known
+ *   type, where the member is deprecated on the static type of the object.
+ * - the code dynamically calls a method with an argument where the
+ *   corresponding optional parameter is deprecated on the object's static type.
+ *
+ *
+ * If the deprecated use is inside a library, class or method which is itself
+ * deprecated, the tool should not bother the user about it.
+ * A deprecated feature is expected to use other deprecated features.
+ */
+class Deprecated {
+  /**
+   * A description of when the deprecated feature is expected to be retired.
+   */
+  final String expires;
+
+  /**
+   * Create a deprecation annotation which specifies the expiration of the
+   * annotated feature.
+   *
+   * The [expires] argument should be readable by programmers, and should state
+   * when an annotated feature is expected to be removed.
+   * This can be specified, for example, as a date, as a release number, or
+   * as relative to some other change (like "when bug 4418 is fixed").
+   */
+  const Deprecated(String expires) : this.expires = expires;
+
+  String toString() => "Deprecated feature. Will be removed $expires";
+}
+
+class _Override {
+  const _Override();
+}
+
+/**
+ * Marks a feature as [Deprecated] until the next release.
+ */
+const deprecated = const Deprecated("next release");
+
+/*
+ * The annotation "@override" marks an instance member as overriding a
+ * superclass member with the same name.
+ *
+ * The annotation applies to instance methods, getters and setters, and to
+ * instance fields, where it means that the implicit getter and setter of the
+ * field is marked as overriding, but the field itself is not.
+ *
+ * A tool may report if no declaration of an annotated member is inherited by
+ * the class from either a superclass or an interface.
+ *
+ * The intent of the "override" notation is to catch situations where a
+ * superclass renames a member, and an independent subclass which used to
+ * override the member, could silently continue working using the
+ * superclass implementation.
+ *
+ * The "@override" annotation is intentionally not used in the core libraries.
+ * It is intended for the editor, or similar tools, to support user written
+ * code.
+ */
+const override = const _Override();