Updating `ImageDownloader` actor sample to support cancellation?

[vanvoorden (Rick van Voorden)]

@ibex

@vanvoorden

actor CountedTask<Success> where Success : Sendable {
  private let task: Task<Success, any Error>
  private var count = 0
  
  init(_ operation: sending @escaping () async throws -> Success) {
    self.task = Task (operation: operation)
    //                           ^
    // Error: Cannot convert value of type 'nonisolated(nonsending) () async throws -> Success' to expected argument type '@isolated(any) () async throws -> Success'
  }

How do I tackle the above error?

I do not see that error. Which toolchain are you compiling from? I can compile from 6.2 and the 6.3 RC with no errors. I do see a 6.4 error… but this is answered from the other thread:

Sendable Closures that are also isolated and synchronous?

Does anyone have advice for defining or passing an isolated and synchronous closure that should also be Sendable? Suppose I start with an actor. I need to perform some work with withTaskCancellationHandler. I begin an operation and run a handler if this task is cancelled. actor A { func operation() { } func handler() { } func f1() async { await withTaskCancellationHandler( operation: self.operation, onCancel: self.handler ) } } This compiles wit…

If you wanted to ship a legit CountedTask in a real product I think it would just need to copy over the different flavors of Task constructors and then forward those parameters to its task variable.