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Please, Without using Android, is there a way i can switch context to a main thread inside a launch ...
# coroutines
p
Please, Without using Android, is there a way i can switch context to a main thread inside a launch {} ?
o
it is the same way as on android -- unless you're not using JavaFX/Swing/etc., and in that case you would need to implement the MainDispatcher yourself to indicate to Kotlin which thread is your "main" thread
p
Yeah, i'm neither using JavaFX or Swing... can you guide me on how to implement a main dispatcher perhaps a link will help.
@octylFractal
t
Since you can't dispatch back to the first thread (the thread that called the 
main
function) on non-UI application due to the lack of an event loop, you could use 
newSingleThreadContext()
to create a dispatcher to use as your main thread. Note that you'll have to block the first thread (with 
runBlocking
and 
withContext
, or using 
launch
and awaiting on the resulting job), otherwise the program will terminate.
o
https://gist.github.com/octylFractal/4fb0ff0fe7fb25cb26d173ba1b3fcbf1 is a small + quick sample for a main dispatcher that does dispatch back to the main thread
only issue being that it doesn't quit 😛 you probably already have some sort of event loop with an exit flag you can put in place of the 
while
loop though
p
Alright... That made me feel like a dummy 🤦‍♂️ . I'm disappointed at my efforts in coding, like how did you come up with that so quick, how did you know about 
ArbitraryMainDispatcher
etc... What am i not reading right?
@octylFractal
o
well, I just wrote 
ArbitraryMainDispatcher
based on the 
JavaFX
main dispatcher, and gave it 
queue(Runnable)
as a stand-in for JavaFX's 
Platform.runLater(Runnable)
. The main part is knowing that 
MainCoroutineDispatcher
exists
p
Alright, followed you on keybase.! thanks
👍 1
t
Don't feel bad about it @paulex, I thought I knew a lot about coroutines until I saw @octylFractal's answer. Let's learn from each other!
👍 1
💪 1
🤣 2
🤗 2
z
The coroutines library already provides a binding of 
Dispatchers.Main
for javafx, is there some reason you can't use that? https://github.com/Kotlin/kotlinx.coroutines/blob/master/ui/kotlinx-coroutines-javafx/README.md
o
z
Oops, I missed the “neither”, my bad
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