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Fix the issue where AtomEffectBuilder fails to demangle witness for the resulting type of multiple blocks #193

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Merged
merged 1 commit into from
Jun 18, 2025
+50 −69
Merged

Fix the issue where AtomEffectBuilder fails to demangle witness for the resulting type of multiple blocks #193

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119 changes: 50 additions & 69 deletions Sources/Atoms/Effect/AtomEffectBuilder.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -19,17 +19,19 @@
@MainActor
@resultBuilder
public enum AtomEffectBuilder {
public static func buildBlock() -> some AtomEffect {
EmptyEffect()
}

public static func buildBlock<Effect: AtomEffect>(_ effect: Effect) -> Effect {
effect
}

public static func buildBlock<each Effect: AtomEffect>(_ effect: repeat each Effect) -> some AtomEffect {
if #available(iOS 17, macOS 14, tvOS 17, watchOS 10, *) {
return BlockEffect(repeat each effect)
}
else {
return BlockBCEffect(repeat each effect)
}
// NB: The combination of variadic type and opaque return type in iOS 16 fails to demangle
// the witness for the return type, which causes a runtime crash.
// Once iOS 16 support is dropped, this function will be changed to return an opaque type.
public static func buildBlock<each Effect: AtomEffect>(_ effect: repeat each Effect) -> BlockEffect {
BlockEffect(repeat each effect)
}

public static func buildIf<Effect: AtomEffect>(_ effect: Effect?) -> some AtomEffect {
Expand All @@ -54,6 +56,46 @@ public enum AtomEffectBuilder {
}

public extension AtomEffectBuilder {
// Use type pack once it is available in iOS 17 or newer.
// struct BlockEffect<each Effect: AtomEffect>: AtomEffect
struct BlockEffect: AtomEffect {
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Copilot AI Jun 18, 2025

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Consider annotating BlockEffect (and its initializer and methods) with @MainActor to enforce actor isolation and prevent potential threading issues, aligning with the @MainActor context of AtomEffectBuilder.

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private let _initializing: @MainActor (Context) -> Void
private let _initialized: @MainActor (Context) -> Void
private let _updated: @MainActor (Context) -> Void
private let _released: @MainActor (Context) -> Void

internal init<each Effect: AtomEffect>(_ effect: repeat each Effect) {
_initializing = { context in
repeat (each effect).initializing(context: context)
}
_initialized = { context in
repeat (each effect).initialized(context: context)
}
_updated = { context in
repeat (each effect).updated(context: context)
}
_released = { context in
repeat (each effect).released(context: context)
}
Comment on lines +68 to +79
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Copilot AI Jun 18, 2025

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[nitpick] The initializer and the related closure properties (_initializing, _initialized, etc.) are repetitive. Consider abstracting the repeated logic—e.g., iterating over a collection of effects in a single closure—to reduce boilerplate.

Suggested change
_initializing = { context in
repeat (each effect).initializing(context: context)
}
_initialized = { context in
repeat (each effect).initialized(context: context)
}
_updated = { context in
repeat (each effect).updated(context: context)
}
_released = { context in
repeat (each effect).released(context: context)
}
_initializing = createEffectHandler(effect: repeat each effect, method: { $0.initializing(context:) })
_initialized = createEffectHandler(effect: repeat each effect, method: { $0.initialized(context:) })
_updated = createEffectHandler(effect: repeat each effect, method: { $0.updated(context:) })
_released = createEffectHandler(effect: repeat each effect, method: { $0.released(context:) })
}
private func createEffectHandler<each Effect: AtomEffect>(
effect: repeat each Effect,
method: @escaping (Effect) -> (Context) -> Void
) -> @MainActor (Context) -> Void {
return { context in
repeat method(each effect)(context)
}

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}

public func initializing(context: Context) {
_initializing(context)
}

public func initialized(context: Context) {
_initialized(context)
}

public func updated(context: Context) {
_updated(context)
}

public func released(context: Context) {
_released(context)
}
}

struct ConditionalEffect<TrueEffect: AtomEffect, FalseEffect: AtomEffect>: AtomEffect {
internal enum Storage {
case trueEffect(TrueEffect)
Expand Down Expand Up @@ -108,68 +150,7 @@ public extension AtomEffectBuilder {
}

private extension AtomEffectBuilder {
@available(iOS 17, macOS 14, tvOS 17, watchOS 10, *)
struct BlockEffect<each Effect: AtomEffect>: AtomEffect {
private let effect: (repeat each Effect)

init(_ effect: repeat each Effect) {
self.effect = (repeat each effect)
}

func initializing(context: Context) {
repeat (each effect).initializing(context: context)
}

func initialized(context: Context) {
repeat (each effect).initialized(context: context)
}

func updated(context: Context) {
repeat (each effect).updated(context: context)
}

func released(context: Context) {
repeat (each effect).released(context: context)
}
}

struct BlockBCEffect: AtomEffect {
private let _initializing: @MainActor (Context) -> Void
private let _initialized: @MainActor (Context) -> Void
private let _updated: @MainActor (Context) -> Void
private let _released: @MainActor (Context) -> Void

init<each Effect: AtomEffect>(_ effect: repeat each Effect) {
_initializing = { context in
repeat (each effect).initializing(context: context)
}
_initialized = { context in
repeat (each effect).initialized(context: context)
}
_updated = { context in
repeat (each effect).updated(context: context)
}
_released = { context in
repeat (each effect).released(context: context)
}
}

func initializing(context: Context) {
_initializing(context)
}

func initialized(context: Context) {
_initialized(context)
}

func updated(context: Context) {
_updated(context)
}

func released(context: Context) {
_released(context)
}
}
struct EmptyEffect: AtomEffect {}

struct IfEffect<Effect: AtomEffect>: AtomEffect {
private let effect: Effect?
Expand Down