Does the position of super.function() causes execution issues in the code?

Question

I wonder whether the placement of the super.function() in flutter/dart affects the execution of the rest of the code, for. eg. creating and disposing a controller.

For. eg.

  @override
  void foo() {
    super.function();
    controller.function();
  }

If I had the super.function() after controller.function() or any code inside those braces, will the code become buggy? Or am I supposed to put it before controller.function()

Note: I have generalized the code

I hope that this answers your question somewhat, as it's a similar idea. https://stackoverflow.com/a/1168356 — dylan-myers, Nov 21 '19 at 10:17
Thanks @dylan-myers for your comment! Yes, they are similar. However, I had this question specifically for dart/flutter as their working might be different than Java. For eg. dart has asynchronity built in by design. If the working of dart/flutter itself in the basics are similar to other languages like java, then yes, my question is answered. — SowingFiber, Nov 21 '19 at 10:55

score 2 · Accepted Answer · answered Nov 21 '19 at 11:28

The question is not that simple as you may think and the answer depends on what you want to achieve.

If you want to override something before the super implementation is executed then you call super after you override what you want to override. For example:

class DoTheMathAndPrint {
   int first = 1;
   int second = 2;


   void iWillDoTheMathAndPrint() {
      int sum = first + second;
      print("The sum is $sum");
   }
}

class NoIWillDoTheMath extends DoTheMathAndPrint {

  @override
  void iWillDoTheMathAndPrint() {
     first = 3;
     second = 5;
     super.iWillDoTheMathAndPrint();
     // will print The sum is 8;
  }
}

If you want the normal flow and then "extend" the flow you will call super first then you'll execute your code. For example:

class WellIHateMath extends DoTheMathAndPrint {

  @override
  void iWillDoTheMathAndPrint() {
    super.iWillDoTheMathAndPrint();
    print("I hope it printed $3");
  }
}

Now, what I usually do when i work with subclasses of frameworks (Flutter, Android, iOS), i decide if a method is "constructive" or "destructive". The "constructive" methods would be some that initialise pieces of code, configurations etc (like initState in flutter). For this kind of methods I call super first, I want to be sure that everything is set up by the framework then I can do my things.

For "destructive" methods, the kind that clean up the resources, free memory etc, (like dispose() in flutter) i call super last, I free my resources then I can say to the framework: "all good, do your job".

There is one thing in dart, that it was a shock for me (because I didn't read enough), is the super call when you use mixins. You have to be very careful with this, the super won't be called on the super class, it will be called on the mixin. For example:

class SomeAwesomeState<T extends StatefulWidget> extends State<T> {

   List<SomeBigObject> _theList = ...smething big;


  @override
  void dispose() {
    _theList.clear();
    super.dispose();
  } 
}

class MyStateWithAnimation extends SomeAwesomeState<AnimationWidget> with SingleTickerProviderStateMixin {

   // some awesome animations here

  @override
  void dispose() {
    //remove whatever here
    super.dispose(); => this will be the super on the SingleTickerProviderStateMixin not on the SomeAwesomeState
  }
}

Does the position of super.function() causes execution issues in the code?

1 Answers1