Created
September 26, 2018 03:29
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Example CancellationToken[Source] a la .net. Provides a way to signal that an operation has been canceled
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| import 'package:w_common/func.dart'; | |
| /// Provides a way to signal that an operation has been canceled. | |
| /// | |
| /// Typically, the consumer creates a [CancellationTokenSource] and then passes | |
| /// the [token] to another operation. The consumer can then call [cancel], | |
| /// while the operation can only check if it has been canceled. | |
| /// | |
| /// FUTURE: If we want a stream to listen for when a cancellation has happened, | |
| /// use CancelableCompleter from the async package instead. | |
| class CancellationTokenSource { | |
| CancellationToken _token; | |
| bool _isCancellationRequested = false; | |
| CancellationTokenSource() { | |
| _token = new CancellationToken(() { | |
| return _isCancellationRequested; | |
| }); | |
| } | |
| CancellationToken get token => _token; | |
| /// Signal to the [token] bearer that they should cancel | |
| void cancel() { | |
| _isCancellationRequested = true; | |
| } | |
| } | |
| /// Provides a way to check if an operation should be canceled. | |
| class CancellationToken { | |
| final Func<bool> isCancellationRequested; | |
| CancellationToken(this.isCancellationRequested); | |
| } |
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