Created
June 7, 2024 06:57
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Lazy and AsyncLazy initializator for Dart / Flutter applications
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| import 'dart:async'; | |
| class AsyncLazy<T> { | |
| static final _cache = Expando(); | |
| final FutureOr<T> Function() _factory; | |
| final FutureOr Function(T)? _valueDispose; | |
| const AsyncLazy(this._factory, [this._valueDispose]); | |
| bool get isInitialized => _cache[this] != null; | |
| FutureOr<T> call() async { | |
| _cache[this] ??= await _factory(); | |
| return _cache[this] as T; | |
| } | |
| Future dispose() async { | |
| if (!isInitialized) { | |
| return; | |
| } | |
| await _valueDispose?.call(await this()); | |
| _cache[this] = null; | |
| } | |
| } |
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| class Lazy<T> { | |
| static final _cache = Expando(); | |
| final T Function() _factory; | |
| final void Function(T)? _valueDispose; | |
| const Lazy(this._factory, [this._valueDispose]); | |
| bool get isInitialized => _cache[this] != null; | |
| T call() { | |
| _cache[this] ??= _factory(); | |
| return _cache[this] as T; | |
| } | |
| void dispose() { | |
| if (!isInitialized) { | |
| return; | |
| } | |
| _valueDispose?.call(this()); | |
| _cache[this] = null; | |
| } | |
| } |
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