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Use KVO to invalidate LazilyDecoding properties

This commit is contained in:
Shadowfacts 2022-12-14 19:46:02 -05:00
parent cacc8a51cc
commit df7b62e14b
1 changed files with 8 additions and 2 deletions
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10
Tusker/LazilyDecoding.swift
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@ -11,13 +11,13 @@ import Foundation
private let decoder = PropertyListDecoder() private let decoder = PropertyListDecoder()
private let encoder = PropertyListEncoder() private let encoder = PropertyListEncoder()
// todo: invalidate cache on underlying data change using KVO?
@propertyWrapper @propertyWrapper
public struct LazilyDecoding<Enclosing, Value: Codable> { public struct LazilyDecoding<Enclosing: NSObject, Value: Codable> {
private let keyPath: ReferenceWritableKeyPath<Enclosing, Data?> private let keyPath: ReferenceWritableKeyPath<Enclosing, Data?>
private let fallback: Value private let fallback: Value
private var value: Value? private var value: Value?
private var observation: NSKeyValueObservation?
init(from keyPath: ReferenceWritableKeyPath<Enclosing, Data?>, fallback: Value) { init(from keyPath: ReferenceWritableKeyPath<Enclosing, Data?>, fallback: Value) {
self.keyPath = keyPath self.keyPath = keyPath
@ -39,6 +39,12 @@ public struct LazilyDecoding<Enclosing, Value: Codable> {
do { do {
let value = try decoder.decode(Box<Value>.self, from: data) let value = try decoder.decode(Box<Value>.self, from: data)
wrapper.value = value.value wrapper.value = value.value
wrapper.observation = instance.observe(wrapper.keyPath, changeHandler: { instance, _ in
var updated = instance[keyPath: storageKeyPath]
updated.value = nil
updated.observation = nil
instance[keyPath: storageKeyPath] = updated
})
instance[keyPath: storageKeyPath] = wrapper instance[keyPath: storageKeyPath] = wrapper
return value.value return value.value
} catch { } catch {