Mixins and Base Classes : A recipe for success in Flutter

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When developing an app with multiple screens, we tend to reuse the same piece of code over many classes: showing error messages, using the same page layout and wiring up some dependencies like for example a Bloc. All this could be solved if were using an abstract base class, however, what if we have a set of features/classes that we want to use on a particular screen but not on others? Since a class can't be a child of more than one class, should we create different base classes, as much as the number of combinations that we have? That's why we have mixins.

Mixins and Base Classes: An introduction

Mixins let us add a set of “features” to a class without using parent-child hierarchy, allowing us to have in the same class one parent and multiple mixin components. As such, since it’s not a parent of our class, mixins don't allow any declaration of constructors. You can read more about them in this article by Romain Rastel with the caveat that Dart 2 now has the mixin keyword, as seen in the documentation.

But how do mixins work? Let's take as an example an abstract class Person