How can i properly pass the value of a async function so i c

Question

How can i properly pass the value of a async function so i can use outside it I need to do 1 for each block like `val bar = async foo ` Or there s a way to do like `async val bar = foo ` and then use bar value

gildor · Answer

What do you try to achieve Do you have some context use case

gildor · Answer

It looks that you don t need async in this case

Fernando Branbila Cunha Junior · Answer

I m trying to learn co routines Saw some tutorials but i m still kind lost What i m trying to archive is to use N suspended functions and to retrive the value of them and use on a non suspended function Like ```fun main val val1 = async func1 val val2 = async func2 val1 await println val2 ```

gildor · Answer

Just drop all async you don t need them Async is required only to do work in parallel concurrently but nothing is parallel in this example all operations are sequential

gildor · Answer

I recommend to read official guide especially this part <https kotlinlang org docs reference coroutines composing suspending functions html|https kotlinlang org docs reference coroutines composing suspending functions html>

Fernando Branbila Cunha Junior · Answer

i undertand that in this example i don t get any paralellism and it isn t a great applicability but it s an example of what i m trying to do to understand more but i m kind lost mainly on how to use values generateded by async calls

Saurabh · Answer

You can do something like this `val deferred = async foo ` `val bar = deferred await `

Fernando Branbila Cunha Junior · Answer

hmm will try to Thanks I ve been strugling on doing something like a CRUD specifically on a return a list of objects using coroutines

uli · Answer

you need a coroutine try `runBlocking ` ```fun main runBlocking val val1 = func1 val val2 = func2 val1 println val2 ``` In the special case of `main` you can also declare main as suspending ```suspend fun main val val1 = func1 val val2 = func2 val1 println val2 ```

gildor · Answer

<https kotlinlang slack com archives C1CFAFJSK p1599749942211100 thread ts=1599743109 208100 amp cid=C1CFAFJSK|https kotlinlang slack com archives C1CFAFJSK p1599749942211100 thread ts=1599743109 208100 amp cid=C1CFAFJSK> It will not work Use runBlocking as Uli suggested it s a way to connect standard functions and suspend asynchronous functions

gildor · Answer

I think you confusion comes from wrong approach to switching between blocking and asynchronous code as you doing it in your simple example 3 times you should try to use different approach you launch coroutine with runBlocking launch or suspend main and do all work there and switch back to blocking code and use runBlocking only in special cases like block program while it executing switching multiple times between blocking and asynchronous code not only with coroutines is usually not the best strategy it requires more blocked threads and just not very efficient

Saurabh · Answer

My bad Didn t see the replies Thought the OP is already inside a coroutine scope sweat smile

gildor · Answer

If it already in coroutine scope then there is no reason to use async and next line call await on it it s the same as just remove async completely and just inline code from async lambda

Saurabh · Answer

Of course you wouldn t do async await like this But you have to look at the fact that the question is not about practical implications of coroutines I thought the question was simpler and about trying to return a value out of an async block

gildor · Answer

gt I ve been strugling on doing something like a CRUD specifically on a return a list of objects using coroutines What kind issue do you have exactly You can return list of objects with coroutines or you want to get each item from this list asynchronously If so see awaitAll function and extension with the same name idea is create multiple Deferred using async and await all of them together as result you will get a list of resulting values