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https://issues.apache.org/jira/browse/GROOVY-9381?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18030796#comment-18030796
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Daniel Sun commented on GROOVY-9381:
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Adding native {{async/await}} would act as a _universal adapter_ or
_simplification layer_ on top of all these libraries. It would bridge the gap
between their complex, specific APIs and a simple, standard, imperative-looking
syntax.
{{async/await}} is just syntactic sugar for consuming a "future-like" object.
The key is that it would need to be designed to "await" not just one native
type, but any "awaitable" object, including those from other libraries.
The API of other libraries should adapt the interface {{Awaitable}} of Groovy
to be used in {{async/await}}.
> Support async/await like ES7
> ----------------------------
>
> Key: GROOVY-9381
> URL: https://issues.apache.org/jira/browse/GROOVY-9381
> Project: Groovy
> Issue Type: New Feature
> Reporter: Daniel Sun
> Priority: Major
>
> Here is an example to show proposed syntax and backend API(Java's
> {{CompletableFuture}} or GPars's {{{}Promise{}}}), but I think it's better
> for Groovy to have its own {{Promise}} to decouple with Java API because
> async/await as a language feature should be as stable as possible.
> {{async}} will generate the {{Awaitable}} instance such as Groovy {{Promise}}
> implementing the {{Awaitable}} interface, and {{await}} can wait for any
> {{Awaitable}} instance to complete and unwrap it for the result.
> {code:java}
> /**
> * 1. An async function that simulates a network API call.
> * The 'async' keyword implies it runs asynchronously without blocking.
> */
> async fetchUserData(userId) {
> println "Starting to fetch data for user ${userId}..."
>
> // Simulate a 1-second network delay.
> Thread.sleep(1000)
>
> println "Fetch successful!"
> // The 'async' function implicitly returns a "CompletableFuture" or
> "Promise" containing this value.
> return [userId: userId, name: 'Daniel']
> }
> /**
> * 2. An async function that uses 'await' to consume the result.
> */
> async processUserData() {
> println "Process started, preparing to fetch user data..."
>
> try {
> // 'await' pauses this function until fetchUserData completes
> // and returns the final result directly.
> def user = await fetchUserData(1)
>
> println "Data received: ${user}"
> return "Processing complete for ${user.name}."
>
> } catch (Exception e) {
> return "An error occurred: ${e.message}"
> }
> }
> // --- Execution ---
> println "Script starting..."
> // Kick off the entire asynchronous process.
> def future = processUserData()
> // This line executes immediately, proving the process is non-blocking.
> println "Script continues to run while user data is being fetched in the
> background..."
> def result = future.get()
> println "Script finished: ${result}"
> {code}
> Use async/await with closure or lambda expression:
> {code:java}
> // use closure
> def future = async {
> println "Process started, preparing to fetch user data..."
>
> try {
> // 'await' pauses this function until fetchUserData completes
> // and returns the final result directly.
> def user = await fetchUserData(1)
>
> println "Data received: ${user}"
> return "Processing complete for ${user.name}."
>
> } catch (Exception e) {
> return "An error occurred: ${e.message}"
> }
> }
> {code}
> {code:java}
> // use lambda expression
> def future = async () -> {
> println "Process started, preparing to fetch user data..."
>
> try {
> // 'await' pauses this function until fetchUserData completes
> // and returns the final result directly.
> def user = await fetchUserData(1)
>
> println "Data received: ${user}"
> return "Processing complete for ${user.name}."
>
> } catch (Exception e) {
> return "An error occurred: ${e.message}"
> }
> }
> {code}
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