Abstract Factory Pattern in Dart: Flutter Guide
Abstract factory is a factory of factories: one interface creating entire families of related objects. Here's the Dart build using Material vs. Cupertino widget families.
Abstract factory = one interface that creates entire *families* of related objects, with the concrete family chosen once and every product guaranteed to match. In Flutter terms: a single WidgetFamilyFactory whose Material implementation hands you ElevatedButton + Switch and whose Cupertino implementation hands you CupertinoButton + CupertinoSwitch — and your screens never contain a single if (Platform.isIOS) . This guide is the abstract factory pattern Dart tutorial built around that Material-vs-Cupertino running example, wired into a real app — plus the decision table for when factory method is the better call. What you'll build The four roles of the pattern (abstract products, abstract factory, concrete factories, client) in Dart 3 A WidgetFamilyFactory with Material and Cupertino families: buttons and switches A Flutter settings screen that consumes the factory with zero platform branches One decision point that selects the family at startup A decision table: abstract factory vs. factory method vs. simple factory Five mistakes that turn the pattern into over-engineering (and the fixes) The idea in 60 seconds Every abstract factory has four roles: Abstract products — the interfaces: DialogButton , ToggleSwitch . The client programs against these, never concrete widgets. Abstract factory — the interface declaring one creation method per product: createButton() , createSwitch() . Concrete factories — one per family: MaterialFamilyFactory creates Material products; CupertinoFamilyFactory creates Cupertino products. Products from one factory always match each other. Client — your screens. They receive a factory and call createButton() without knowing or caring which family is active. The guarantee is the point: you can never accidentally pair a Material button with a…