Flutter 中的所有小部件是否都具有“bool this.mounted”属性？

Question

Peace be upon you

I am researching Flutter's widget lifecycle and stopped at a point which is the this.mounted boolean variable, it does exist directly in the State class, which can only be connected with a StatefulWidget as a subclass and never will/did with a StatelessWidget .

The question is...

Do all widgets actually contain the bool this.mounted variable as some say here in [ this accepted answer , this article and this ], or not?

I searched in Flutter and found this mounted variable only in the State class, then I looked further to find a function called mount() inside the Element class.

The StatelessWidget class is connected to the StatelessElement class, which extends from the ComponentElement that inherits directly from the Element class.

I'm really confused right now, maybe I misunderstood this, I need an explanation for this please,. Thank you.

Answer 1

In the future versions of Flutter (currently 3.3.4 on the stable channel) BuildContext will have a getter bool mounted so you can use it in stateless widgets:

See this PR which adds the getter: https://github.com/flutter/flutter/pull/111619

Update:

This has been released with Flutter 3.7.0 . You can now use context.mounted in stateful and stateless widgets.

Answer 2

Not sure why that answers says all widgets . But NO .

Only State<T> objects are the ones that have a getter named mounted .

This is easy to verify, Just cmd + click or ctrl + click on any State you have in your class which will redirect you to a file called framework.dart which is located at flutter -> package -> flutter -> lib -> src -> widgets path.

Search mounted and this line is the only actual declaration that you will find.

bool get mounted => _element != null;

And that's part of the State class' code.