I m new to coroutines and struggling to get my head around t

Question

I m new to coroutines and struggling to get my head around the conceptuals while trying to implement a debounce ```override fun onOptionsItemSelected item MenuItem Boolean return when item itemId R id refresh gt flow callbacks refreshAllTheThings debounce 5000 return true else gt return super onOptionsItemSelected item ``` however I get the following compilation error `Not enough information to infer type variable T` I ve gone and looked at the implementation of `debounce ` but the examples in the comments suggest what I have above should be sufficient Why does flow need type information if I just want to execute one line of code at most every 5 seconds

wasyl · Answer

Flow is a flow of values that you need to collect somehow In your example the error is just a compiler error because you don t emit anything from the flow you create if you just do `flow lt Unit gt ` it would be enough to compile

wasyl · Answer

However it still wouldn t work as you expect because creating a flow doesn t do anything by itself without collecting it

wasyl · Answer

Besides if you want debounce you need to have just one flow for multiple clicks Here you d be creating a separate flow for every click anyway I m not sure how to best implement this with a callback like this though you d probably need a channel to which you post click events and have a debounce on that channel

wasyl · Answer

Something like ```val clicksChannel = BroadcastChannel lt Unit gt 1 fun onOptionsItemSelected clicksChannel offer Unit onCreate lifecycleScope launchWhenCreated clicksChannel asFlow debounce 5000 collect refreshAllThings ```

Andrew Ebling · Answer

great many thanks getting close but I now realise `debounce` is not the behaviour I m looking for more like `throttle` but seems coroutines doesn t use this out of the box

Andrew Ebling · Answer

`debounce` is waiting until the timeout before sending the first event

wasyl · Answer

I m not sure `throttle` exists <https github com Kotlin kotlinx coroutines issues 1446>

Andrew Ebling · Answer

lol just reading through the comments on that exact issue smile

wasyl · Answer

Maybe `sample` would help Not sure

Andrew Ebling · Answer

I think that s done the trick many thanks for your help +1

Andrew Ebling · Answer

Actually I ve learned a tonne with you guidance this morning a whole load of conceptual stuff has fallen into place I m just one of those people who learns far more effectively through seeing working code than reading it all explained in theory

Andrew Ebling · Answer

Thanks again for taking time out of your day

wasyl · Answer

Sure happy to help slightly smiling face