I have a function that should have three required and in best case named parameters. The last one ("finished") should be optional. I tried it like this:
static void showOverlay(BuildContext context, String text, bool successfull,
[VoidCallback? finished]) {}
but Flutter is complaining:
Avoid positional boolean parameters
The weird thing is that it is only complaining about the bool successfull. What am I doing wrong here and how can I fix this?
Named parameters are by default optional. So in your case it would be:
static void showOverlay({BuildContext context, String text, bool successfull, VoidCallback? finished}) {}
Notice the {} in the constructor, this makes your parameters named and optional. By using @required in front of your declaration, you can differentiate between required and not required.
you can use it like this using positional parameters
void showOverlay(BuildContext context, String text, bool successful, [VoidCallback finished]) {}
or like this using named parameters
void showOverlay({@required BuildContext context, @required String text, @required bool successful, VoidCallback finished}) {}
and dart is complaining becuase named parameters is best practice as mentioned in dart docs
Positional boolean parameters are a bad practice because they are very ambiguous. Using named boolean parameters is much more readable because it inherently describes what the boolean value represents.
BAD:
Task(true);
Task(false);
ListBox(false, true, true);
Button(false);
GOOD:
Task.oneShot();
Task.repeating();
ListBox(scroll: true, showScrollbars: true);
Button(ButtonState.enabled);
Named parameters are optional unless they’re specifically marked as required.
Below, all four of your parameters are named. Three are required while one of them is optional.
static void showOverlay({required BuildContext context, required String text,
required bool successfull, VoidCallback? finished}) {}