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noboru-i/main.dart

Last active August 30, 2023 03:49
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Call async function from non-async function
Raw
readme.md

Call async function from non-async function

Created with <3 with dartpad.dev.

DartPadでの実行結果は以下のようになった。 https://dartpad.dev/?id=6bc0451f6b97182649eb07c5ab31f51c

main: before someFutureFunc
someFutureFunc: before wait
main: after someFutureFunc
(3秒程度経った後、次が表示される）
someFutureFunc: after wait
  • non-async functionでは、 await することが出来ない。
  • async function 内で、 await をするまでは、同期的に実行される。（おそらく）
  • await した時点で制御が戻り、 main function側の続きが実行される（おそらく）
  • async function 内は、そのまま処理が継続される（処理系に依存する？）
Raw
main.dart
void main() {
print('main: before someFutureFunc');
someFutureFunc();
print('main: after someFutureFunc');
}
Future<void> someFutureFunc() async {
print('someFutureFunc: before wait');
await Future.delayed(const Duration(seconds: 3));
print('someFutureFunc: after wait');
}
@noboru-i
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noboru-i commented Aug 30, 2023

https://dart.dev/codelabs/async-await#execution-flow-with-async-and-await

Execution flow with async and await
An async function runs synchronously until the first await keyword. This means that within an async function body, all synchronous code before the first await keyword executes immediately.

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