for case let ... where

Swift ⟩ Pattern Matching ⟩ Sentence Patterns ⟩

• case: pattern matching.

• let: variable binding.

• where: condition on bound variable.

💈範例

💾 程式： Mirror.handleChildren()

⭐️ 注意： for case let ... where 加條件的方式跟 if/guard case let 不一樣❗️

// mirror of `subject`
let mirror = Mirror(reflecting: subject)

// ⭐ for case let ... where 
//   (pattern-match tuples + data binding + condition)
// ------------------------------------------------------
//            ↱ ⭐ child.label ignored     ╭── ⭐ where ───╮
for case let (_, value) in mirror.children where value is T {
    // ...
}

// ⭐ for case let ... where
for case let .loaded(data) in states where data.count > 2
{ ... }

⭐️ 重點

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