Responding to `FooClient.Action` regardless of which view generates `Effect`s emitting them

Related Projects Swift Composable Architecture
2

Hey Joe,

we haven't talked about this at all yet and don't have any documentation on it, and there are a few ways to approach this. One interesting way is to create a higher-order reducer that can allow sharing actions from one reducer to another.

For example, this:

extension Reducer {
  func resending<Value>(
    _ case: @escaping (Value) -> Action,
    to embed: @escaping (Value) -> Action
  ) -> Self {
    .combine(
      self,
      .init { state, action, _ in
        if let value = CasePath.case(`case`).extract(from: action) {
          return Effect(value: embed(value))
        } else {
          return .none
        }
      }
    )
  }
}

You can tack that onto an existing reducer to make any of its action be automatically re-sent to another reducer:

parentReducer
  .resending(ParentAction.fooClient, to: { ParentAction.child1(.fooClient($0)) })
  .resending(ParentAction.fooClient, to: { ParentAction.child2(.fooClient($0)) })
...

I'd be curious how that fits your use case.

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