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1 // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file |
2 // for details. All rights reserved. Use of this source code is governed by a | 2 // for details. All rights reserved. Use of this source code is governed by a |
3 // BSD-style license that can be found in the LICENSE file. | 3 // BSD-style license that can be found in the LICENSE file. |
4 | 4 |
5 library observe.src.bindable; | 5 library observe.src.bindable; |
6 | 6 |
7 /// An object that can be data bound. | 7 /// An object that can be data bound. |
8 // Normally this is used with 'package:template_binding'. | 8 // Normally this is used with 'package:template_binding'. |
9 // TODO(jmesserly): Node.bind polyfill calls this "observable" | 9 // TODO(jmesserly): Node.bind polyfill calls this "observable" |
10 abstract class Bindable { | 10 abstract class Bindable { |
11 // TODO(jmesserly): since we have "value", should open be a void method? | |
12 // Dart note: changed setValue to be "set value" and discardChanges() to | 11 // Dart note: changed setValue to be "set value" and discardChanges() to |
13 // be "get value". Also "set value" implies discard changes. | 12 // be "get value". Also "set value" implies discard changes. |
Siggi Cherem (dart-lang)
2014/07/07 19:41:14
I guess we can now remove the "Also ..."
| |
14 // TOOD(jmesserly): is this change too subtle? Is there any other way to | 13 // TODO(jmesserly): is this change too subtle? Is there any other way to |
15 // make Bindable friendly in a world with getters/setters? | 14 // make Bindable friendly in a world with getters/setters? |
16 | 15 |
17 /// Initiates observation and returns the initial value. | 16 /// Initiates observation and returns the initial value. |
18 /// The callback will be called with the updated [value]. | 17 /// The callback will be called with the updated [value]. |
19 /// | 18 /// |
20 /// Some subtypes may chose to provide additional arguments, such as | 19 /// Some subtypes may chose to provide additional arguments, such as |
21 /// [PathObserver] providing the old value as the second argument. | 20 /// [PathObserver] providing the old value as the second argument. |
22 /// However, they must support callbacks with as few as 0 or 1 argument. | 21 /// However, they must support callbacks with as few as 0 or 1 argument. |
23 /// This can be implemented by performing an "is" type test on the callback. | 22 /// This can be implemented by performing an "is" type test on the callback. |
24 open(callback); | 23 open(callback); |
25 | 24 |
26 /// Stops future notifications and frees the reference to the callback passed | 25 /// Stops future notifications and frees the reference to the callback passed |
27 /// to [open], so its memory can be collected even if this Bindable is alive. | 26 /// to [open], so its memory can be collected even if this Bindable is alive. |
28 void close(); | 27 void close(); |
29 | 28 |
30 /// Gets the current value of the bindings. | 29 /// Gets the current value of the bindings. |
30 /// Note: once the value of a [Bindable] is fetched, the callback passed to | |
31 /// [open] should not be called again with this new value. | |
32 /// In other words, any pending change notifications must be discarded. | |
33 // TODO(jmesserly): I don't like a getter with side effects. Should we just | |
34 // rename the getter/setter pair to discardChanges/setValue like they are in | |
35 // JavaScript? | |
31 get value; | 36 get value; |
32 | 37 |
33 /// This can be implemented for two-way bindings. By default does nothing. | 38 /// This can be implemented for two-way bindings. By default does nothing. |
34 /// Note: setting the value of a [Bindable] must not call the [callback] with | |
35 /// the new value. Any pending change notifications must be discarded. | |
36 set value(newValue) {} | 39 set value(newValue) {} |
40 | |
41 /// Deliver changes. Typically this will perform dirty-checking, if any is | |
42 /// needed. | |
43 void deliver() {} | |
37 } | 44 } |
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