The Promise library is a Java based implementation of the Promise A+ specification. As part of the implementation we added the ability to unpack list results for chaining and track overall status of the chain as a whole. Additionally, there is a deduplication feature which detects equivalent calls on promise functions and short circuits the response.
Basic use with concrete class:
Promise<String> promise = new PromiseImpl<String>();
promise.then(new FixedValueFunction<>("didSomething"));
promise.fulfill("value");
Basic use with lambda:
Promise<String> promise = new PromiseImpl<String>();
promise.thenSync(value -> "didSomething");
promise.fulfill("value");
Basic use with async lambda:
Promise<String> promise = new PromiseImpl<String>();
promise.thenAsync(value -> new DefaultPromiseFuture("didSomething"));
promise.fulfill("value");
Basic use for lists:
PromiseList<String> promise = new PromiseListImpl<String>();
promise.map().then(new FixedValueFunction<>("didSomethingOncePerItemInList"));
promise.fulfill(Arrays.asList("one", "two"));
Perform operation after chain completes:
Promise<String> promise = new PromiseImpl<String>();
promise.then(new FixedValueFunction<>("didSomething"));
promise.after().then(new FixedValueFunction<>("success"), new FixedValueFuncion<>("failure"));
Mark promise optional (default is false):
Promise<String> promise = new PromiseImpl<String>();
future.thenSync(value -> { throw new Exception("failed"); }).optional(true);
promise.fulfill("value");
promise.after().then(new FixedValueFunction<>("success"), new FixedValueFuncion<>("failure"));
Prevent duplicate work (default is true):
Promise<String> promise = new PromiseImpl<String>().nonduplicating(true);
promise.then(new FixedValueFunction<>("didSomething"));
promise.then(new FixedValueFunction<>("didSomething"));
promise.fulfill("value");
Prerequisites:
Building:
promise> mvn verify
To use the local version you must first install it locally:
promise> mvn install
You can determine the version of the local build from the pom file. Using the local version is intended only for testing or development.
Published under Apache Software License 2.0, see LICENSE
© Groupon Inc., 2015