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Optional+Let.swift
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extension Optional { | |
mutating func `let`(handler: (inout Wrapped) -> Void) { | |
self = map { | |
var wrapped = $0 | |
handler(&wrapped) | |
return wrapped | |
} | |
} | |
} |
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struct Dog { | |
var apples = 10 | |
mutating func eat() { | |
apples -= 1 | |
} | |
} | |
var dog: Dog? = .init() | |
// Before | |
// 毎回 nil チェックするのが冗長 | |
// dog?.eat() | |
// dog?.eat() | |
// dog?.eat() | |
// After | |
// Kotlin の `let()` と同じように使える | |
dog.let { | |
$0.eat() | |
$0.eat() | |
$0.eat() | |
} | |
print(String(describing: dog?.apples) // Optional(7) |
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ref: https://twitter.com/marty_suzuki/status/1438910538981859330?s=20