Sorry for more one question but I am trying understand more about coroutine and

kable

is a great use case.

private val job = SupervisorJob(parentCoroutineContext.job) 
private val scope = CoroutineScope(parentCoroutineContext + job)
private val connectionScope = CoroutineScope(scope.coroutineContext + Job(scope.coroutineContext[Job]))

Here is what I understood about the code quoted above:

scope

inherits parent's context but with new

job

. That

job

is a

SupervisorJob

so if any child of

scope

fails or is cancelled it manage each one separately (if one child fail or cancel the others child continue working and the parent also is not cancelled)

job

inherits parent's job. If parent is cancelled all the child also is cancelled. Here is what I did not understand:

connectionScope

inherits context and job of

scope

. Are they the same????

One way to look at it is: The plus operator for coroutine context properties replaces the previous element. So, in your example,

connectionScope

will have all the same

CoroutineContext

elements except its

Job

will have been overwritten by the

Job(parentJob)

that you did. It will essentially be a copy of

scope

but with its parent being

scope

. Otherwise anything that was configured previously on that

CoroutineContext

such as exception handlers or dispatches, will be the same on the two scopes. This is a great article on the topic: https://proandroiddev.com/demystifying-coroutinecontext-1ce5b68407ad

I got the sample code from Kable library 😄. I understand now.

The Job is what is used for cancellation, so your connectionScope will have all the same dispatchers as scope, but you can now cancel it and it won't cancel scope (because they have different Jobs).

But if I cancel

connectionScope

with exception different of

CancellationException

so

scope

is also cancelled, right???

If you're referring to Kable, the

scope

is configured with a parent: https://github.com/JuulLabs/kable/blob/main/core/src/androidMain/kotlin/Peripheral.kt#L144 The parent scope is the receiver of the

peripheral

extension function. So, whenever you create a peripheral, you decide what you want the parent

CoroutineScope

to be. If you cancel the scope used as the receiver of the

peripheral

extension function then the `Peripheral`'s internal

scope

will be cancelled.