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Is there any particular reason why `StateFlow/MutableStateFlow` doesn’t implement `ReadOnlyProperty/ReadWriteProperty`? It seems like it’s a perfect fit for a thread-safe property.

probably because a significant number of usages of StateFlow are not properties

but there may be a good use case for making a separate class that implements ReadOnlyProperty/ReadWriteProperty using a StateFlow/MutableStateFlow

You don’t actually need to implement them. Extension functions work just as well.

I was just surprised it’s not built-in, as it seems like such an obvious use, so I was wondering if I’m missing something.

```val stateFlow: MutableStateFlow&lt;T&gt; = ...
var flowValue: T by stateFlow::value```
it doesn't need to be built into StateFlow specifically, the stdlib already contains all the extensions needed to make the above work

Sure, but I’d like to use it without declaring a separate property:
```var counter by MutableStateFlow(1)```

```var counter by MutableStateFlow(1)::value```
but why?

Hmm, didn’t think of that.
Why? Because `StateFlow` is thread-safe

Is there a delegate specifically for thread-safety?

if you don’t have a separate property to store the flow, then you don’t need a flow.

The only reason you need a flow is if you need to observe it.

You can’t observe it if you never store the flow anywhere else

If your problem is needing a threadsafe property, I would not use Flow for that.

what aspect of thread safety do you need? if it's simply observability across all threads, then a `@Volatile` field works for every type except `Long` and `Double`

Yes, observability across threads. I don’t want to do a JVM-specific annotation, and as you said, it doesn’t work for 64-bit values.

I guess the better question is why there is no `Delegates.synchronized(…)`

synchronization itself is not cross-platform

kotlinx.coroutines uses kotlinx.atomicfu under the hood, which does provide delegates for its atomic types

yeah good call ephemient, <https://github.com/Kotlin/kotlinx.atomicfu>