blob: c3314a2b112b8431b291784e8f0eac3c6111efec [file] [log] [blame]
// 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.
library observe.src.bindable;
/// An object that can be data bound.
// Normally this is used with 'package:template_binding'.
// TODO(jmesserly): Node.bind polyfill calls this "observable"
abstract class Bindable {
// Dart note: changed setValue to be "set value" and discardChanges() to
// be "get value".
/// Initiates observation and returns the initial value.
/// The callback will be called with the updated [value].
/// Some subtypes may chose to provide additional arguments, such as
/// [PathObserver] providing the old value as the second argument.
/// However, they must support callbacks with as few as 0 or 1 argument.
/// This can be implemented by performing an "is" type test on the callback.
/// Stops future notifications and frees the reference to the callback passed
/// to [open], so its memory can be collected even if this Bindable is alive.
void close();
/// Gets the current value of the bindings.
/// Note: once the value of a [Bindable] is fetched, the callback passed to
/// [open] should not be called again with this new value.
/// In other words, any pending change notifications must be discarded.
// TODO(jmesserly): I don't like a getter with side effects. Should we just
// rename the getter/setter pair to discardChanges/setValue like they are in
// JavaScript?
get value;
/// This can be implemented for two-way bindings. By default does nothing.
set value(newValue) {}
/// Deliver changes. Typically this will perform dirty-checking, if any is
/// needed.
void deliver() {}