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Fix typo in BindingAction.pullback(_:) docs (#830)
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‎Sources/ComposableArchitecture/SwiftUI/Binding.swift‎

Lines changed: 133 additions & 133 deletions
Original file line numberDiff line numberDiff line change
@@ -298,11 +298,11 @@ import SwiftUI
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///
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/// See the documentation for ``BindableState`` for more details.
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public struct BindingAction<Root>: Equatable {
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public let keyPath: PartialKeyPath<Root>
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public let keyPath: PartialKeyPath<Root>
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let set: (inout Root) -> Void
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let value: Any
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let valueIsEqualTo: (Any) -> Bool
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let set: (inout Root) -> Void
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let value: Any
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let valueIsEqualTo: (Any) -> Bool
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public static func == (lhs: Self, rhs: Self) -> Bool {
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lhs.keyPath == rhs.keyPath && lhs.valueIsEqualTo(rhs.value)
@@ -356,135 +356,135 @@ import SwiftUI
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#endif
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extension BindingAction {
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/// Transforms a binding action over some root state to some other type of root state given a
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/// key path.
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///
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/// Useful in transforming binding actions on view state into binding actions on reducer state
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/// when the domain contains ``BindableState`` and ``BindableAction``.
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///
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/// For example, we can model an app that can bind an integer count to a stepper and make a
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/// network request to fetch a fact about that integer with the following domain:
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///
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/// ```swift
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/// struct AppState: Equatable {
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/// @BindableState var count = 0
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/// var fact: String?
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/// ...
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/// }
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///
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/// enum AppAction: BindableAction {
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/// case binding(BindingAction<AppState>
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/// case factButtonTapped
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/// case factResponse(String?)
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/// ...
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/// }
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///
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/// struct AppEnvironment {
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/// var numberFact: (Int) -> Effect<String, Error>
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/// ...
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/// }
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///
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/// let appReducer = Reducer<AppState, AppAction, AppEnvironment> {
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/// ...
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/// }
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/// .binding()
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///
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/// struct AppView: View {
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/// let store: Store
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///
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/// var view: some View {
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/// ...
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/// }
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/// }
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/// ```
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///
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/// The view may want to limit the state and actions it has access to by introducing a
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/// view-specific domain that contains only the state and actions the view needs. Not only will
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/// this minimize the number of times a view's `body` is computed, it will prevent the view
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/// from accessing state or sending actions outside its purview. We can define it with its own
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/// bindable state and bindable action:
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///
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/// ```swift
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/// extension AppView {
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/// struct ViewState: Equatable {
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/// @BindableState var count: Int
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/// let fact: String?
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/// // no access to any other state on `AppState`, like child domains
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/// }
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///
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/// enum ViewAction: BindableAction {
416-
/// case binding(BindingAction<ViewState>)
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/// case factButtonTapped
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/// // no access to any other action on `AppAction`, like `factResponse`
419-
/// }
420-
/// }
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/// ```
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///
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/// In order to transform a `BindingAction<ViewState>` sent from the view domain into a
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/// `BindingAction<AppState>`, we need a writable key path from `AppState` to `ViewState`. We
425-
/// can synthesize one by defining a computed property on `AppState` with a getter and a setter.
426-
/// The setter should communicate any mutations to bindable state back to the parent state:
427-
///
428-
/// ```swift
429-
/// extension AppState {
430-
/// var view: AppView.ViewState {
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/// get { .init(count: self.count, fact: self.fact) }
432-
/// set { self.count = newValue.count }
433-
/// }
434-
/// }
435-
/// ```
436-
///
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/// With this property defined it is now possible to transform a `BindingAction<ViewState>` into
438-
/// a `BindingAction<AppState>`, which means we can transform a `ViewAction` into an
439-
/// `AppAction`. This is where `pullback` comes into play: we can unwrap the view action's
440-
/// binding action on view state and transform it with `pullback` to work with app state. We can
441-
/// define a helper that performs this transformation, as well as route any other view actions
442-
/// to their reducer equivalents:
443-
///
444-
/// ```swift
445-
/// extension AppAction {
446-
/// static func view(_ viewAction: AppView.ViewAction) -> Self {
447-
/// switch viewAction {
448-
/// case let .binding(action):
449-
/// // transform view binding actions into app binding actions
450-
/// return .binding(action.pullback(\.view))
451-
///
452-
/// case let .factButtonTapped
453-
/// // route `ViewAction.factButtonTapped` to `AppAction.factButtonTapped`
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/// return .factButtonTapped
455-
/// }
456-
/// }
457-
/// }
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/// ```
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///
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/// Finally, in the view we can invoke ``Store/scope(state:action:)`` with these domain
461-
/// transformations to leverage the view store's binding helpers:
462-
///
463-
/// ```swift
464-
/// WithViewStore(
465-
/// self.store.scope(state: \.view, action: AppAction.view)
466-
/// ) { viewStore in
467-
/// Stepper("\(viewStore.count)", viewStore.binding(\.$count))
468-
/// Button("Get number fact") { viewStore.send(.factButtonTapped) }
469-
/// if let fact = viewStore.fact {
470-
/// Text(fact)
471-
/// }
472-
/// }
473-
/// ```
474-
///
475-
/// - Parameter keyPath: A key path from a new type of root state to the original root state.
476-
/// - Returns: A binding action over a new type of root state.
477-
public func pullback<NewRoot>(
478-
_ keyPath: WritableKeyPath<NewRoot, Root>
479-
) -> BindingAction<NewRoot> {
480-
.init(
481-
keyPath: (keyPath as AnyKeyPath).appending(path: self.keyPath) as! PartialKeyPath<NewRoot>,
482-
set: { self.set(&$0[keyPath: keyPath]) },
483-
value: self.value,
484-
valueIsEqualTo: self.valueIsEqualTo
485-
)
486-
}
487-
}
359+
/// Transforms a binding action over some root state to some other type of root state given a
360+
/// key path.
361+
///
362+
/// Useful in transforming binding actions on view state into binding actions on reducer state
363+
/// when the domain contains ``BindableState`` and ``BindableAction``.
364+
///
365+
/// For example, we can model an app that can bind an integer count to a stepper and make a
366+
/// network request to fetch a fact about that integer with the following domain:
367+
///
368+
/// ```swift
369+
/// struct AppState: Equatable {
370+
/// @BindableState var count = 0
371+
/// var fact: String?
372+
/// ...
373+
/// }
374+
///
375+
/// enum AppAction: BindableAction {
376+
/// case binding(BindingAction<AppState>)
377+
/// case factButtonTapped
378+
/// case factResponse(String?)
379+
/// ...
380+
/// }
381+
///
382+
/// struct AppEnvironment {
383+
/// var numberFact: (Int) -> Effect<String, Error>
384+
/// ...
385+
/// }
386+
///
387+
/// let appReducer = Reducer<AppState, AppAction, AppEnvironment> {
388+
/// ...
389+
/// }
390+
/// .binding()
391+
///
392+
/// struct AppView: View {
393+
/// let store: Store
394+
///
395+
/// var view: some View {
396+
/// ...
397+
/// }
398+
/// }
399+
/// ```
400+
///
401+
/// The view may want to limit the state and actions it has access to by introducing a
402+
/// view-specific domain that contains only the state and actions the view needs. Not only will
403+
/// this minimize the number of times a view's `body` is computed, it will prevent the view
404+
/// from accessing state or sending actions outside its purview. We can define it with its own
405+
/// bindable state and bindable action:
406+
///
407+
/// ```swift
408+
/// extension AppView {
409+
/// struct ViewState: Equatable {
410+
/// @BindableState var count: Int
411+
/// let fact: String?
412+
/// // no access to any other state on `AppState`, like child domains
413+
/// }
414+
///
415+
/// enum ViewAction: BindableAction {
416+
/// case binding(BindingAction<ViewState>)
417+
/// case factButtonTapped
418+
/// // no access to any other action on `AppAction`, like `factResponse`
419+
/// }
420+
/// }
421+
/// ```
422+
///
423+
/// In order to transform a `BindingAction<ViewState>` sent from the view domain into a
424+
/// `BindingAction<AppState>`, we need a writable key path from `AppState` to `ViewState`. We
425+
/// can synthesize one by defining a computed property on `AppState` with a getter and a setter.
426+
/// The setter should communicate any mutations to bindable state back to the parent state:
427+
///
428+
/// ```swift
429+
/// extension AppState {
430+
/// var view: AppView.ViewState {
431+
/// get { .init(count: self.count, fact: self.fact) }
432+
/// set { self.count = newValue.count }
433+
/// }
434+
/// }
435+
/// ```
436+
///
437+
/// With this property defined it is now possible to transform a `BindingAction<ViewState>` into
438+
/// a `BindingAction<AppState>`, which means we can transform a `ViewAction` into an
439+
/// `AppAction`. This is where `pullback` comes into play: we can unwrap the view action's
440+
/// binding action on view state and transform it with `pullback` to work with app state. We can
441+
/// define a helper that performs this transformation, as well as route any other view actions
442+
/// to their reducer equivalents:
443+
///
444+
/// ```swift
445+
/// extension AppAction {
446+
/// static func view(_ viewAction: AppView.ViewAction) -> Self {
447+
/// switch viewAction {
448+
/// case let .binding(action):
449+
/// // transform view binding actions into app binding actions
450+
/// return .binding(action.pullback(\.view))
451+
///
452+
/// case let .factButtonTapped
453+
/// // route `ViewAction.factButtonTapped` to `AppAction.factButtonTapped`
454+
/// return .factButtonTapped
455+
/// }
456+
/// }
457+
/// }
458+
/// ```
459+
///
460+
/// Finally, in the view we can invoke ``Store/scope(state:action:)`` with these domain
461+
/// transformations to leverage the view store's binding helpers:
462+
///
463+
/// ```swift
464+
/// WithViewStore(
465+
/// self.store.scope(state: \.view, action: AppAction.view)
466+
/// ) { viewStore in
467+
/// Stepper("\(viewStore.count)", viewStore.binding(\.$count))
468+
/// Button("Get number fact") { viewStore.send(.factButtonTapped) }
469+
/// if let fact = viewStore.fact {
470+
/// Text(fact)
471+
/// }
472+
/// }
473+
/// ```
474+
///
475+
/// - Parameter keyPath: A key path from a new type of root state to the original root state.
476+
/// - Returns: A binding action over a new type of root state.
477+
public func pullback<NewRoot>(
478+
_ keyPath: WritableKeyPath<NewRoot, Root>
479+
) -> BindingAction<NewRoot> {
480+
.init(
481+
keyPath: (keyPath as AnyKeyPath).appending(path: self.keyPath) as! PartialKeyPath<NewRoot>,
482+
set: { self.set(&$0[keyPath: keyPath]) },
483+
value: self.value,
484+
valueIsEqualTo: self.valueIsEqualTo
485+
)
486+
}
487+
}
488488

489489
#if compiler(>=5.4)
490490
extension Reducer where Action: BindableAction, State == Action.State {

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