API: Memoized Selectors Reference


                    
                    
                    createSelector(_:transformation:memoized:)

Higher order function that creates a composable, optimized selector function. A selector function is a pure function used for obtaining slices of store state.

Example: The following shows a composable, memoized selectVisibleBooks selector function.

Composable: We depend on the selectUser and selectAllBooks selectors to filter only the books belonging to the selectedUser, if one exists.

Memoized: By using the default memoized = true parameter, if the allMovies section slice of the state changes, the transformation in selectVisibleBooks would not recompute.

struct AppState {
var selectedUser: User?
var allBooks: [Book] = []
var allMovies: [Movie] = []
}
let selectUser = { (state: AppState) in state.selectedUser }
let selectAllBooks = { (state: AppState) in state.allBooks }

let selectVisibleBooks = createSelector( selectUser, selectAllBooks, transformation: { (selectedUser, allBooks) -> [Book] in if let selectedUser = selectedUser { return allBooks.filter { (book: Book) in book.userId == selectedUser.id } } else { return allBooks } } )

Declaration

Swift

public func createSelector<
    S: Equatable,
    V: Equatable,
    T
    >(_ selectorFn: @escaping SelectorFn<S, V>,
      transformation: @escaping (V) -> T,
      memoized: Bool = true
) -> SelectorFn<S, T>

Parameters

`selectorFn`	Up to nine selector functions. The result of each selector function will be used as input to the `transformation` parameter’s closure.
`transformation`	A projector function used to derive, transform or combine data from the state slices passed to it and return this modified data as a single object - typically for direct view consumption.
`memoized`	True by default. If true, will cache the result from the last input. Prevents unnecessary recomputation if dependent state slices do not change.


                    
                    
                    createSelector(_:_:transformation:memoized:)

See documentation in createSelector(_:transformation:memoized:).

Declaration

Swift

public func createSelector<
    S: Equatable,
    V1: Equatable,
    V2: Equatable,
    T
    >(_ selectorFn1: @escaping SelectorFn<S, V1>,
      _ selectorFn2: @escaping SelectorFn<S, V2>,
      transformation: @escaping (V1, V2) -> T,
      memoized: Bool = true
) -> SelectorFn<S, T>


                    
                    
                    createSelector(_:_:_:transformation:memoized:)

See documentation in createSelector(_:transformation:memoized:).

Declaration

Swift

public func createSelector<
    S: Equatable,
    V1: Equatable,
    V2: Equatable,
    V3: Equatable,
    T
    >(_ selectorFn1: @escaping SelectorFn<S, V1>,
      _ selectorFn2: @escaping SelectorFn<S, V2>,
      _ selectorFn3: @escaping SelectorFn<S, V3>,
      transformation: @escaping (V1, V2, V3) -> T,
      memoized: Bool = true
) -> SelectorFn<S, T>


                    
                    
                    createSelector(_:_:_:_:transformation:memoized:)

See documentation in createSelector(_:transformation:memoized:).

Declaration

Swift

public func createSelector<
    S: Equatable,
    V1: Equatable,
    V2: Equatable,
    V3: Equatable,
    V4: Equatable,
    T
    >(_ selectorFn1: @escaping SelectorFn<S, V1>,
      _ selectorFn2: @escaping SelectorFn<S, V2>,
      _ selectorFn3: @escaping SelectorFn<S, V3>,
      _ selectorFn4: @escaping SelectorFn<S, V4>,
      transformation: @escaping (V1, V2, V3, V4) -> T,
      memoized: Bool = true
) -> SelectorFn<S, T>


                    
                    
                    createSelector(_:_:_:_:_:transformation:memoized:)

See documentation in createSelector(_:transformation:memoized:).

Declaration

Swift

public func createSelector<
    S: Equatable,
    V1: Equatable,
    V2: Equatable,
    V3: Equatable,
    V4: Equatable,
    V5: Equatable,
    T
    >(_ selectorFn1: @escaping SelectorFn<S, V1>,
      _ selectorFn2: @escaping SelectorFn<S, V2>,
      _ selectorFn3: @escaping SelectorFn<S, V3>,
      _ selectorFn4: @escaping SelectorFn<S, V4>,
      _ selectorFn5: @escaping SelectorFn<S, V5>,
      transformation: @escaping (V1, V2, V3, V4, V5) -> T,
      memoized: Bool = true
) -> SelectorFn<S, T>


                    
                    
                    createSelector(_:_:_:_:_:_:transformation:memoized:)

See documentation in createSelector(_:transformation:memoized:).

Declaration

Swift

public func createSelector<
    S: Equatable,
    V1: Equatable,
    V2: Equatable,
    V3: Equatable,
    V4: Equatable,
    V5: Equatable,
    V6: Equatable,
    T
    >(_ selectorFn1: @escaping SelectorFn<S, V1>,
      _ selectorFn2: @escaping SelectorFn<S, V2>,
      _ selectorFn3: @escaping SelectorFn<S, V3>,
      _ selectorFn4: @escaping SelectorFn<S, V4>,
      _ selectorFn5: @escaping SelectorFn<S, V5>,
      _ selectorFn6: @escaping SelectorFn<S, V6>,
      transformation: @escaping (V1, V2, V3, V4, V5, V6) -> T,
      memoized: Bool = true
) -> SelectorFn<S, T>


                    
                    
                    createSelector(_:_:_:_:_:_:_:transformation:memoized:)

See documentation in createSelector(_:transformation:memoized:).

Declaration

Swift

public func createSelector<
    S: Equatable,
    V1: Equatable,
    V2: Equatable,
    V3: Equatable,
    V4: Equatable,
    V5: Equatable,
    V6: Equatable,
    V7: Equatable,
    T
    >(_ selectorFn1: @escaping SelectorFn<S, V1>,
      _ selectorFn2: @escaping SelectorFn<S, V2>,
      _ selectorFn3: @escaping SelectorFn<S, V3>,
      _ selectorFn4: @escaping SelectorFn<S, V4>,
      _ selectorFn5: @escaping SelectorFn<S, V5>,
      _ selectorFn6: @escaping SelectorFn<S, V6>,
      _ selectorFn7: @escaping SelectorFn<S, V7>,
      transformation: @escaping (V1, V2, V3, V4, V5, V6, V7) -> T,
      memoized: Bool = true
) -> SelectorFn<S, T>


                    
                    
                    createSelector(_:_:_:_:_:_:_:_:transformation:memoized:)

See documentation in createSelector(_:transformation:memoized:).

Declaration

Swift

public func createSelector<
    S: Equatable,
    V1: Equatable,
    V2: Equatable,
    V3: Equatable,
    V4: Equatable,
    V5: Equatable,
    V6: Equatable,
    V7: Equatable,
    V8: Equatable,
    T
    >(_ selectorFn1: @escaping SelectorFn<S, V1>,
      _ selectorFn2: @escaping SelectorFn<S, V2>,
      _ selectorFn3: @escaping SelectorFn<S, V3>,
      _ selectorFn4: @escaping SelectorFn<S, V4>,
      _ selectorFn5: @escaping SelectorFn<S, V5>,
      _ selectorFn6: @escaping SelectorFn<S, V6>,
      _ selectorFn7: @escaping SelectorFn<S, V7>,
      _ selectorFn8: @escaping SelectorFn<S, V8>,
      transformation: @escaping (V1, V2, V3, V4, V5, V6, V7, V8) -> T,
      memoized: Bool = true
) -> SelectorFn<S, T>


                    
                    
                    createSelector(_:_:_:_:_:_:_:_:_:transformation:memoized:)

See documentation in createSelector(_:transformation:memoized:).

Declaration

Swift

public func createSelector<
    S: Equatable,
    V1: Equatable,
    V2: Equatable,
    V3: Equatable,
    V4: Equatable,
    V5: Equatable,
    V6: Equatable,
    V7: Equatable,
    V8: Equatable,
    V9: Equatable,
    T
    >(_ selectorFn1: @escaping SelectorFn<S, V1>,
      _ selectorFn2: @escaping SelectorFn<S, V2>,
      _ selectorFn3: @escaping SelectorFn<S, V3>,
      _ selectorFn4: @escaping SelectorFn<S, V4>,
      _ selectorFn5: @escaping SelectorFn<S, V5>,
      _ selectorFn6: @escaping SelectorFn<S, V6>,
      _ selectorFn7: @escaping SelectorFn<S, V7>,
      _ selectorFn8: @escaping SelectorFn<S, V8>,
      _ selectorFn9: @escaping SelectorFn<S, V9>,
      transformation: @escaping (V1, V2, V3, V4, V5, V6, V7, V8, V9) -> T,
      memoized: Bool = true
) -> SelectorFn<S, T>