Extends vs Mixin

In Flutter, mixins and extends are both used to achieve code reuse, but they are used in different ways.

extends is used to create a subclass that inherits properties and methods from a superclass. This allows you to create a new class that is a modified version of an existing class, with the ability to override or add additional functionality as needed.

class Animal {
  void makeNoise() {
    print('Some noise');
  }
}

class Dog extends Animal {
  @override
  void makeNoise() {
    print('Bark');
  }
}

In this example, the Dog class extends the Animal class and overrides the makeNoise method to print "Bark" instead of the default "Some noise".

mixins, on the other hand, are used to provide a set of methods that can be used by multiple classes, without requiring the classes to inherit from a common superclass. This is useful when you want to share functionality between unrelated classes, or when a class can't inherit from multiple superclasses (since Dart, like many object-oriented languages, doesn't support multiple inheritance).

mixin Barking {
  void bark() {
    print('Bark');
  }
}

class Dog with Barking {}

class Cat with Barking {}

In this example, both the Dog and Cat classes can use the bark method, even though they are unrelated and don't share a common superclass.

It’s worth noting that mixins are implemented using inheritance under the hood, but they don't have the same behavior as inheritance. For example, a class that uses a mixin doesn't inherit the mixin's constructors, and the mixin's methods are not automatically overridden by the class's methods.