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Modules/BusX/BusUI/src/BusUI.ManyValue.swift

@@ -0,0 +1,42 @@
+import Combine
+
+extension BusUI {
+  public final class Value<T>: ObservableObject {
+    let key: String
+    @Published public var id: String?
+    @Published public var v: T
+    var sub = [AnyCancellable]()
+    var subscriptions = [AnyCancellable]()
+   
+    public init(
+      _ key: String,
+      _ defaultValue: T
+    ) {
+      self.key = key
+      v = defaultValue
+
+      $id
+        .sink { [weak self] id in self?.setup(id) }
+        .store(in: &sub)
+    }
+
+    private func setup(_ id: String?) {
+      subscriptions = []
+
+      Bus.receiveSync(
+        [key],
+        { [weak self] (_, m: MPAK.Many<T>) in
+          guard
+            let id,
+            m.keys.contains(id),
+            let v = m.dict[id]
+          else {
+            return
+          }
+          self?.v = v
+        },
+        &subscriptions
+      )
+    }
+  }
+}