Hmm i m still unsure of how coroutines will be used in real

Question

Hmm i m still unsure of how coroutines will be used in real life situations other than syntactic sugar to avoid call back hell is there anything it provides

louiscad · Answer

Can be used for async I O can be used to await events like the code was blocking a thread but without blocking a thread I see plenty of usages where doing so without coroutines would require a callback hell if even possible I personally use coroutines for Bluetooth Low Energy connections <https github com Beepiz BleGattCoroutines>

asad.awadia · Answer

`can be used to await events like the code was blocking a thread but without blocking a thread` lt this is exactly what I thought they provided too do u have any examples

hiperbou · Answer

I use coroutines to encapsulate and to have a clean and common way to use all the async functions of third party libraries for example some lib uses promises gt coroutine other uses callbacks gt coroutine other signals gt coroutine keeps my code clean and readable

louiscad · Answer

< asad awadia> Let s say you want to await an internet connection before attempting your network call You could write a function that would suspend until there s an internet connection Then you would call `awaitInternetConnection ` in a coroutine a suspend block and your code would go past the `awaitInternetConnection ` call only when the internet connection is there that is when the method resumes from suspension and would do this without blocking any thread or locking up precious ressources

louiscad · Answer

< asad awadia> Such behavior can implemented in different ways I made a similar thing that suspends until a Bluetooth Low Energy connection is performed which relies on this `Gate` class

asad.awadia · Answer

is `awaitInternetConnection ` a suspend function or is it of the form `fun awaitInternatConnection = launch code `

asad.awadia · Answer

but if i call it in a `runBlocking` it will block the thread which voids the whole point correct

louiscad · Answer

It can only work if `awaitInternetConnection ` is a suspend function

asad.awadia · Answer

but what if the code inside the awaitInternetConnection is blocking

asad.awadia · Answer

the suspend doesn t do anything right the code inside needs to be non blocking in the first place

louiscad · Answer

runBlocking blocks the thread making it available solely for the coroutine inside the block It is useful on JVM not Android to avoid the main thread to terminate and allows to use it in a coroutines context

louiscad · Answer

What blocking code are you expecting in an `awaitInternetConnection ` function

asad.awadia · Answer

wouldn t waiting for a connection inherently be blocking

louiscad · Answer

What I call blocking code is code that does synchronous I O or significant computations CPU computations should be done in `CommonPool` most of the time Blocking I O should be done on a thread pool properly sized for the running environment like you d do in Java but for prototyping having a global top level `val IO = CommonPool` is okay as long as it doesn t locks up CPU bound computations that are normally the stuff `CommonPool` is made for

louiscad · Answer

You then use `CommonPool` `IO` or other coroutine contexts as arguments for `async ` and `launch `

louiscad · Answer

And no waiting for an internet connection is not inherently blocking In Android for example you get a callback in a BroadcastReceiver when connectivity changes where you can check again if the active connection if any is connected to internet You could then feed this to a `BroadcastChannel` consumed by various parts of your program or feed it to a class like the `Gate` class I showed you earlier that could the be used to write a suspending `awaitInternetConnection ` suspend function