Change Store to use Signal pipe instead of MutableProperty.

Author: mluisbrown

Sources/ComposableArchitecture/Internal/Deprecations.swift

@@ -76,7 +76,7 @@
         [ID], (Data.Index, EachAction), ForEach<[(offset: Int, element: ID)], ID, EachContent>
       >
     {
-      let data = store.$state.value
+      let data = store.state
       self.data = data
       self.content = {
         WithViewStore(store.scope(state: { $0.map { $0[keyPath: id] } })) { viewStore in

Sources/ComposableArchitecture/Store.swift

@@ -114,8 +114,15 @@ import ReactiveSwift
 /// See also: ``ViewStore`` to understand how one observes changes to the state in a ``Store`` and
 /// sends user actions.
 public final class Store<State, Action> {
-  @MutableProperty
-  private(set) var state: State
+  private(set) var state: State {
+    didSet {
+      statePipe.input.send(value: state)
+    }
+  }
+  private let statePipe = Signal<State, Never>.pipe()
+  internal var producer: Effect<State, Never> {
+    Property<State>(initial: self.state, then: self.statePipe.output.producer).producer
+  }
 
   private var isSending = false
   private let reducer: (inout State, Action) -> Effect<Action, Never>
@@ -294,11 +301,11 @@ public final class Store<State, Action> {
       environment: ()
     )
 
-    localStore.parentDisposable = self.$state.producer
+    localStore.parentDisposable = self.producer
       .skip(first: 1)
       .startWithValues { [weak localStore] newValue in
         guard !isSending else { return }
-        localStore?.$state.value = toLocalState(newValue)
+        localStore?.state = toLocalState(newValue)
       }
 
     return localStore
@@ -333,7 +340,7 @@ public final class Store<State, Action> {
       return localState
     }
 
-    return toLocalState(self.$state.producer)
+    return toLocalState(self.producer)
       .map { localState in
         let localStore = Store<LocalState, LocalAction>(
           initialState: localState,
@@ -344,7 +351,7 @@ public final class Store<State, Action> {
           },
           environment: ()
         )
-        localStore.parentDisposable = self.$state.producer.startWithValues {
+        localStore.parentDisposable = self.producer.startWithValues {
           [weak localStore] state in
           guard let localStore = localStore else { return }
           localStore.state = extractLocalState(state) ?? localStore.state
@@ -370,10 +377,10 @@ public final class Store<State, Action> {
     guard !self.isSending else { return }
 
     self.isSending = true
-    var currentState = self.$state.value
+    var currentState = self.state
     defer {
       self.isSending = false
-      self.$state.value = currentState
+      self.state = currentState
     }
 
     while !self.bufferedActions.isEmpty {

Sources/ComposableArchitecture/SwiftUI/ForEachStore.swift

@@ -100,7 +100,7 @@
             //     views for elements no longer in the collection.
             //
             // Feedback filed: https://gist.github.com/stephencelis/cdf85ae8dab437adc998fb0204ed9a6b
-            let element = store.$state.value[id: id]!
+            let element = store.state[id: id]!
             return content(
               store.scope(
                 state: { $0[id: id] ?? element },

Sources/ComposableArchitecture/SwiftUI/SwitchStore.swift

@@ -1160,7 +1160,7 @@
         let message = """
           Warning: SwitchStore.body@\(self.file):\(self.line)
 
-              "\(debugCaseOutput(self.store.wrappedValue.$state.value))" was encountered by a \
+              "\(debugCaseOutput(self.store.wrappedValue.state))" was encountered by a \
           "SwitchStore" that does not handle this case.
 
           Make sure that you exhaustively provide a "CaseLet" view for each case in "\(State.self)", \

Sources/ComposableArchitecture/TestSupport/TestStore.swift

@@ -528,7 +528,7 @@
         environment: self.environment,
         file: self.file,
         fromLocalAction: { self.fromLocalAction(fromLocalAction($0)) },
-        initialState: self.store.$state.value,
+        initialState: self.store.state,
         line: self.line,
         reducer: self.reducer,
         toLocalState: { toLocalState(self.toLocalState($0)) }

Sources/ComposableArchitecture/ViewStore.swift

@@ -64,7 +64,7 @@ public final class ViewStore<State, Action> {
 
   private let _send: (Action) -> Void
   private var _state: State
-  fileprivate let _stateSubject = Signal<State, Never>.pipe()
+  fileprivate let statePipe = Signal<State, Never>.pipe()
   private var viewDisposable: Disposable?
 
   /// Initializes a view store from a store.
@@ -77,10 +77,10 @@ public final class ViewStore<State, Action> {
     _ store: Store<State, Action>,
     removeDuplicates isDuplicate: @escaping (State, State) -> Bool
   ) {
-    self._state = store.$state.value
+    self._state = store.state
     self._send = store.send
 
-    self.viewDisposable = store.$state.producer
+    self.viewDisposable = store.producer
       .skipRepeats(isDuplicate)
       .startWithValues { [weak self] in
         guard let self = self else { return }
@@ -90,7 +90,7 @@ public final class ViewStore<State, Action> {
           }
         #endif
         self._state = $0
-        self._stateSubject.input.send(value: $0)
+        self.statePipe.input.send(value: $0)
       }
   }
 
@@ -297,7 +297,7 @@ public struct StoreProducer<State>: SignalProducerConvertible {
 
   fileprivate init<Action>(viewStore: ViewStore<State, Action>) {
     self.viewStore = viewStore
-    self.upstream = Property<State>(initial: viewStore.state, then: viewStore._stateSubject.output).producer
+    self.upstream = Property<State>(initial: viewStore.state, then: viewStore.statePipe.output).producer
 //      .on(completed: { [viewStore = self.viewStore] in
 //        _ = viewStore
 //      })

Tests/ComposableArchitectureTests/StoreTests.swift

@@ -80,7 +80,7 @@ final class StoreTests: XCTestCase {
     let childStore = parentStore.scope(state: String.init)
 
     var values: [String] = []
-    childStore.$state.producer
+    childStore.producer
       .startWithValues { values.append($0) }
 
     XCTAssertEqual(values, ["0"])
@@ -101,7 +101,7 @@ final class StoreTests: XCTestCase {
     let childViewStore = ViewStore(childStore)
 
     var values: [Int] = []
-    parentStore.$state.producer
+    parentStore.producer
       .startWithValues { values.append($0) }
 
     XCTAssertEqual(values, [0])
@@ -123,7 +123,7 @@ final class StoreTests: XCTestCase {
     parentStore
       .producerScope(state: { $0.map { "\($0)" }.skipRepeats() })
       .startWithValues { childStore in
-        childStore.$state.producer
+        childStore.producer
           .startWithValues { outputs.append($0) }
       }
 
@@ -282,7 +282,7 @@ final class StoreTests: XCTestCase {
 
     parentStore
       .producerScope { $0.skipRepeats() }
-      .startWithValues { outputs.append($0.$state.value) }
+      .startWithValues { outputs.append($0.state) }
 
     XCTAssertEqual(outputs, [0])
 
@@ -451,73 +451,73 @@ final class StoreTests: XCTestCase {
   }
 
 // This test commented out as it falls foul of ReactiveSwift's
-// `MutableProperty` not allowing nested modifications 😢
-
-//  func testBufferedActionProcessing() {
-//    struct ChildState: Equatable {
-//      var count: Int?
-//    }
-//
-//    let childReducer = Reducer<ChildState, Int?, Void> { state, action, _ in
-//      state.count = action
-//      return .none
-//    }
-//
-//    struct ParentState: Equatable {
-//      var count: Int?
-//      var child: ChildState?
-//    }
-//
-//    enum ParentAction: Equatable {
-//      case button
-//      case child(Int?)
-//    }
-//
-//    var handledActions: [ParentAction] = []
-//    let parentReducer = Reducer.combine([
-//      childReducer
-//        .optional()
-//        .pullback(
-//          state: \.child,
-//          action: /ParentAction.child,
-//          environment: {}
-//        ),
-//      Reducer<ParentState, ParentAction, Void> { state, action, _ in
-//        handledActions.append(action)
-//
-//        switch action {
-//        case .button:
-//          state.child = .init(count: nil)
-//          return .none
-//
-//        case .child(let childCount):
-//          state.count = childCount
-//          return .none
-//        }
-//      },
-//    ])
-//
-//    let parentStore = Store(
-//      initialState: .init(),
-//      reducer: parentReducer,
-//      environment: ()
-//    )
-//
-//    parentStore
-//      .scope(
-//        state: \.child,
-//        action: ParentAction.child
-//      )
-//      .ifLet { childStore in
-//        ViewStore(childStore).send(2)
-//      }
-//
-//    XCTAssertEqual(handledActions, [])
-//
-//    parentStore.send(.button)
-//    XCTAssertEqual(handledActions, [
-//      .button,
-//      .child(2)
-//    ])
-//  }
+// `Signal` not allowing nested sends 😢
+
+  func disabled_testBufferedActionProcessing() {
+    struct ChildState: Equatable {
+      var count: Int?
+    }
+
+    let childReducer = Reducer<ChildState, Int?, Void> { state, action, _ in
+      state.count = action
+      return .none
+    }
+
+    struct ParentState: Equatable {
+      var count: Int?
+      var child: ChildState?
+    }
+
+    enum ParentAction: Equatable {
+      case button
+      case child(Int?)
+    }
+
+    var handledActions: [ParentAction] = []
+    let parentReducer = Reducer.combine([
+      childReducer
+        .optional()
+        .pullback(
+          state: \.child,
+          action: /ParentAction.child,
+          environment: {}
+        ),
+      Reducer<ParentState, ParentAction, Void> { state, action, _ in
+        handledActions.append(action)
+
+        switch action {
+        case .button:
+          state.child = .init(count: nil)
+          return .none
+
+        case .child(let childCount):
+          state.count = childCount
+          return .none
+        }
+      },
+    ])
+
+    let parentStore = Store(
+      initialState: .init(),
+      reducer: parentReducer,
+      environment: ()
+    )
+
+    parentStore
+      .scope(
+        state: \.child,
+        action: ParentAction.child
+      )
+      .ifLet { childStore in
+        ViewStore(childStore).send(2)
+      }
+
+    XCTAssertEqual(handledActions, [])
+
+    parentStore.send(.button)
+    XCTAssertEqual(handledActions, [
+      .button,
+      .child(2)
+    ])
+  }
 }