So I ve got a bad idea What if we embedded a progress bar co

Question

So I ve got a bad idea What if we embedded a progress bar control and a delegating `CoroutineDispatcher` into a coroutineContext such that we could ~automagically make progress bars based on the number of suspension points I think this is akin to reflecting on the number of states the coroutine state machine has Of course while loops and if statements blow this up but still I feel like there might be something here Has anybody got an implementation doing something like this

groostav · Answer

I m tired of replacing my buggy java based progress bar implementing spagetti code with kotlin coroutine backed code that is way more readable but only renders a spinner

ephemient · Answer

interesting thought but I have no idea how you would count the number of suspension points left to go

gildor · Answer

I don t think it s possible to do on level of coroutine dispatcher

gildor · Answer

Also I don t think that it good enough to just count suspend points

groostav · Answer

< gildor> no but its a start to make it work youd need some pretty heavy static code analysis

groostav · Answer

you could do something like ```fun launchProgressBarableTask subtaskCount Int job suspend gt R Deferred lt R gt suspend fun enterSubtask subtask suspend gt R R ``` usage ```fun onUIEvent launchProgressBarableTask subtaskCount = customers size for customer in customers results += enterSubtask lookupCustomerDetailsFromSlowDB customer publish results ```

groostav · Answer

you dont actually need `enterSubtask` since you can infer it from the dispatch but that seems really brittle to me

groostav · Answer

of course this also is just working with 1 level of the job tree

groostav · Answer

if we knew more about ther size of the job tree ahead of time we could build really high fidelity progress bars

gildor · Answer

wouldn t be easier publish result explicitly

gildor · Answer

I see your point just curious is effort really worth it maybe report progress explicitly is easier to maintain and it provides better progress reporting

gildor · Answer

It also may be pretty idiomatic with right dsl because you alredy have launchProgressBarableTask which may provice custom scope in lambda ```fun onUIEvent launchProgressBarableTask subtaskCount = customers size return mapWithProgress customers customer gt enterSubtask lookupCustomerDetailsFromSlowDB customer ```

gildor · Answer

where `mapWithProgress` is a method of `launchProgressBarableTask` which reports progress for each item of `customers` and report it to `launchProgressBarableTask`