Index: pkg/observe/lib/src/bindable.dart |
diff --git a/pkg/observe/lib/src/bindable.dart b/pkg/observe/lib/src/bindable.dart |
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+// 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 { |
+ // TODO(jmesserly): since we have "value", should open be a void method? |
+ // TODO(jmesserly): not sure how I feel about open taking a variable number |
+ // of arguments, but it's the easiest way to make CompoundObserver work. |
+ |
+ /// 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. |
+ open(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. |
+ get value; |
+ |
+ /// This can be implemented for two-way bindings. By default does nothing. |
+ /// Note: setting the value of a [Bindable] must not call the [callback] with |
+ /// the new value. Any pending change notifications must be discarded. |
+ set value(newValue) {} |
+} |