✨ Adds StateBinding.

Author: connor-ricks

.swiftpm/xcode/xcshareddata/xcschemes/swift-nibbles-Package.xcscheme

@@ -90,6 +90,20 @@
                ReferencedContainer = "container:">
             </BuildableReference>
          </BuildActionEntry>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "StateBinding"
+               BuildableName = "StateBinding"
+               BlueprintName = "StateBinding"
+               ReferencedContainer = "container:">
+            </BuildableReference>
+         </BuildActionEntry>
       </BuildActionEntries>
    </BuildAction>
    <TestAction
@@ -124,6 +138,16 @@
                ReferencedContainer = "container:">
             </BuildableReference>
          </TestableReference>
+         <TestableReference
+            skipped = "NO">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "StateBindingTests"
+               BuildableName = "StateBindingTests"
+               BlueprintName = "StateBindingTests"
+               ReferencedContainer = "container:">
+            </BuildableReference>
+         </TestableReference>
       </Testables>
    </TestAction>
    <LaunchAction

Package.swift

@@ -17,6 +17,7 @@ let package = Package(
         .library(name: "Identified", targets: ["Identified"]),
         .library(name: "SharedState", targets: ["SharedState"]),
         .library(name: "Stash", targets: ["Stash"]),
+        .library(name: "StateBinding", targets: ["StateBinding"]),
         .plugin(name: "Create TCA Feature", targets: ["Create TCA Feature"])
     ],
     dependencies: [
@@ -40,7 +41,10 @@ let package = Package(
 
         .target(name: "Stash"),
         .testTarget(name: "StashTests", dependencies: ["Stash"]),
-        
+
+        .target(name: "StateBinding"),
+        .testTarget(name: "StateBindingTests", dependencies: ["StateBinding", .product(name: "ConcurrencyExtras", package: "swift-concurrency-extras")]),
+
         .plugin(
             name: "Create TCA Feature",
             capability: .command(

Sources/StateBinding/StateBinding.swift

@@ -0,0 +1,49 @@
+//
+// MIT License
+//
+// Copyright (c) 2024 Connor Ricks
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+import SwiftUI
+
+@propertyWrapper
+public struct StateBinding<Value>: DynamicProperty {
+
+    // MARK: Properties
+
+    @State private var state: Value
+
+    public var externalBinding: Binding<Value>? = nil
+
+    public var wrappedValue: Value {
+        get { projectedValue.wrappedValue }
+        nonmutating set { projectedValue.wrappedValue = newValue }
+    }
+
+    public var projectedValue: Binding<Value> {
+        externalBinding ?? $state
+    }
+
+    // MARK: Initializers
+
+    public init(wrappedValue: Value) {
+        _state = .init(initialValue: wrappedValue)
+    }
+}

Tests/StateBindingTests/StateBindingTests.swift

@@ -0,0 +1,54 @@
+//
+// MIT License
+//
+// Copyright (c) 2024 Connor Ricks
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+@testable import StateBinding
+import ConcurrencyExtras
+import SwiftUI
+import XCTest
+
+@MainActor
+class StateBindingTests: XCTestCase {
+    func test_stateBinding_whenProvidedExternalBinding_doesUseExternalBinding() async {
+        let getterExpectation = expectation(description: "Expected binding getter.")
+        getterExpectation.expectedFulfillmentCount = 2
+
+        let setterExpectation = expectation(description: "Expected binding setter.")
+
+        let count = LockIsolated(0)
+        let binding = Binding(
+            get: {
+                getterExpectation.fulfill()
+                return count.value
+            },
+            set: {
+                setterExpectation.fulfill()
+                count.setValue($0)
+            }
+        )
+        @StateBinding var counter = 5
+        _counter.externalBinding = binding
+        binding.wrappedValue = 10
+        XCTAssertEqual(counter, 10)
+        await fulfillment(of: [setterExpectation, getterExpectation], enforceOrder: true)
+    }
+}