$ show reactiveui/ReactiveUI
ReactiveUI is a production-grade, cross-platform MVVM (Model-View-ViewModel) framework for the .NET ecosystem. Its architecture is centered around reactive primitives (ReactiveObject, ReactiveProperty, IObservable) that form the backbone of its view model layer. The framework employs a fluent builder pattern (RxAppBuilder) for application initialization, a custom dependency injection system ('Splat'), and extensive source code generation to provide a type-safe, AOT-compatible binding and view resolution system. It abstracts platform-specific UI toolkits (WPF, WinUI, MAUI, WinForms, AndroidX, iOS/macOS UIKit, Blazor) behind a consistent set of interfaces (IViewFor<T>, IRoutableViewModel, IActivatableViewModel). The codebase demonstrates strong engineering practices, including a sophisticated reactive command pattern (ReactiveCommand), a typed message bus (MessageBus), a state persistence lifecycle (SuspensionHost), and a collection change-set streaming mechanism (ReactiveChangeSet). A significant portion of the code is dedicated to ensuring Ahead-of-Time (AOT) compilation safety, avoiding reflection where possible through generic view resolution and explicit registration, which is a non-trivial and well-executed design constraint. The repository includes extensive unit tests, platform-specific integration tests, and performance benchmarks. While the framework is actively maintained (evidenced by recent commits, low open issue count, and zero Dependabot alerts), its ambitious scope introduces inherent complexity. The reliance on a custom DI framework, conditional compilation flags (REACTIVE_SHIM), and the maintenance burden of supporting eight distinct UI platforms are notable architectural trade-offs. Despite this, the core abstractions are cleanly separated, highly reusable, and represent a high standard of craftsmanship in the .NET reactive programming space.
The LLM identified 6 files worth highlighting for reuse:
Implements the core reactive object pattern for ViewModels. Provides RaiseAndSetIfChanged, SuppressChangeNotifications, and lazy Changing/Changed observables. This is a highly polished, self-contained implementation of the Observable pattern optimized for AOT safety. It can be extracted and reused in any .NET project requiring observable state management.
Implements an observable command with CanExecute, IsExecuting, ThrownExceptions, and Execute() returning IObservable<TResult>. Includes factories for tasks and background operations. This is a robust, reusable implementation of the Command pattern with reactive extensions, extractable for any application needing observable, composable commands.
A typed, observable message bus supporting Listen, ListenIncludeLatest, and RegisterMessageSource. Provides a clean, self-contained implementation of an event bus with strong type safety and lifecycle management. This pattern is directly reusable for decoupled inter-component communication in any application.
Manages application state persistence lifecycle (suspend/resume/invalidate) via an ISuspensionDriver abstraction. Provides reactive signals for ShouldPersistState and IsLaunchingNew. This is a well-abstracted, reusable state management pattern applicable to any application needing structured session persistence.
A fluent builder pattern for composing a complex application at startup. Manages DI setup, platform registration, scheduler configuration, and converter registration. This pattern is highly reusable for any framework or application requiring a structured, extensible initialization sequence.
Provides a reactive stream of collection changes (add, remove, update, move) by adapting INotifyCollectionChanged into an IObservable<IReactiveChangeSet<T>>. This is a sophisticated, self-contained solution to the common problem of observing collection mutations in a reactive pipeline.