content: // 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 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.
   *
   * 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 editor, or a similar tool aimed at the programmer, may report if no
   * declaration of an annotated member is inherited by the class from either a
   * superclass or an interface.
   *
   * Use the `@override` annotation judiciously and only for methods where
   * the superclass is not under the programmer's control, the superclass is in a
   * different library or package, and it is not considered stable.
   * In any case, the use of `@override` is optional.
   *
   * For example, the annotation is intentionally not used in the Dart platform
   * libraries, since they only depend on themselves.
   */
  const Object override = const _Override();
  
  class _Proxy {
    const _Proxy();
  }
  
  /**
   * The annotation `@proxy` marks a class as implementing members through
   * `noSuchMethod`.
   *
   * The annotation applies to concrete classes. It is not inherited by
   * subclasses.
   *
   * The marked class is considerer to implement any method, getter or setter
   * declared by its interface, even if there is no implementation in the
   * class. It will not generate the warning that is otherwise specified for an
   * unimplemented method in a non-abstract class.
   *
   * Tools that understand `@proxy` should tell the user if a class using `@proxy`
   * does not override the `noSuchMethod` declared on [Object].
   *
   * The intent of the `@proxy` notation is to avoid irrelevant warnings when
   * a class implements its interface through `noSuchMethod`.
   */
  const Object proxy = const _Proxy();
  