How to make a function asynchronous?-CodePudding

Why doesn't the execution of f in the following code happen asynchronously after the main function. I expect it to be scheduled for execution from the event loop. Returning some Future doesn't help either.

void f() async {
  print('f');
}


void main() {
  print('main start');
  f();
  print('main end');
}

Output:

main start
f
main end

CodePudding user response：

Marking a function async doesn't make what's going on inside the function async or change how the caller handles it. Any synchronous code inside a function marked async will still be run synchronously until the first async function call is hit.

To call print('f') asynchronously, construct a new Future.

void f() {
  Future(()=>print('f'));
}


void main() {
  print('main start');
  f();
  print('main end');
}

Or you could construct the future in main if you'd like:

void f() {
 print('f');
}


void main() {
  print('main start');
  Future(f);
  print('main end');
}