1

Hi everyone, this is slightly Apple Platform related, but I will try and keep it relatively generic as I think it could be useful on other platforms.

For a bit of context, I am trying to build a Property Wrapper that interacts with the Keychain with the standard CRU functionality, to ensure values are not overwritten in different contexts I have set up my helper object for interacting with the keychain set up as an Actor

I am using this helper object as the "storage" for my Property Wrapper, of course this leads to a problem with concurrent properties, I would like to have the wrappedValue property as a get, set property, but I need to access the helper object in an asynchronous context, because I want to have a setter I cannot have an async getter and I cannot seem to work out how I can access the actor in a synchronous way, I am probably missing something obvious, or I am trying to do something outside of the scope of Property Wrappers/Actors but my google-fu is failing me, so I thought I would ask around here.

I'm not sure it is much help, but this is how I left my code last night:

var wrappedValue: Value {
get { Task { await storage.value } }
set { Task { await storage.update(newValue) } }
}
2

I’m not aware of any way to access actor in a blocking manner. Actors are intended to prevent writing blocking code. If you really need blocking behavior, implementing your storage as a plain class with a mutex inside would be better.

Alternatively, you can maintain a private copy of the data inside main actor (assuming your property wrapper is used in UI code). But make sure to make any writes to the master copy.

3

If you're willing to adopt actors, why not also adopt async properties? Technically, keychain accesses are blocking and should be wrapped asynchronously, so this is the perfect opportunity to adopt a best practice and the new concurrency features at the same time.

1 Like
4

I wanted to be able to write to the property as well, async properties does not support that.

But I think when I moved away to try and use async properties, Property Wrappers don't allow for async contexts in general at the moment, so it is a bit of a no go

1 Like