Table of Contents

Source Generator Application Suite

This example suite shows how PatternKit generators remove boilerplate while preserving explicit application architecture. The examples live under src/PatternKit.Examples/Generators and are validated by test/PatternKit.Examples.Tests/Generators.

The examples are intentionally application-shaped: DI module setup, orchestrated startup steps, generated facades, builder-driven host composition, source-generated strategies, generated mementos, generated state machines, and generated visitors.

Pattern Map

Generator Example source Test source Production shape
Builder src/PatternKit.Examples/Generators/Builders/CorporateApplicationBuilderDemo test/PatternKit.Examples.Tests/Generators/CorporateApplicationBuilderDemoTests.cs Host/application composition similar to ASP.NET Core extension methods.
Factory Method src/PatternKit.Examples/Generators/Factories/FactoryGeneratorExamples.cs test/PatternKit.Examples.Tests/Generators/FactoryGeneratorExamplesTests.cs Configuration keys map to IServiceCollection module wiring.
Factory Class src/PatternKit.Examples/Generators/Factories/FactoryGeneratorExamples.cs test/PatternKit.Examples.Tests/Generators/FactoryGeneratorExamplesTests.cs Startup orchestration steps are selected by stable string keys.
Facade src/PatternKit.Examples/Generators/Facade test/PatternKit.Examples.Tests/Generators/FacadeSpecsTests.cs Billing and shipping subsystem operations are exposed through focused facades.
Memento src/PatternKit.Examples/Generators/Memento test/PatternKit.Examples.Tests/Generators/MementoGeneratorExamplesTests.cs Editor and game state snapshots support undo, restore, and state checkpointing.
State Machine src/PatternKit.Examples/Generators/State/OrderFlowDemo.cs test/PatternKit.Examples.Tests/Generators/StateGeneratorExamplesTests.cs Order lifecycle transitions are generated from explicit state metadata.
Strategy src/PatternKit.Examples/Generators/Strategies/StrategySpecs.cs test/PatternKit.Examples.Tests/Generators/StrategySpecsTests.cs Generated action, result, and try strategies replace repetitive routing scaffolding.
Visitor src/PatternKit.Examples/Generators/Visitors/DocumentProcessingDemo.cs test/PatternKit.Examples.Tests/Generators/VisitorGeneratorExamplesTests.cs Document processing uses generated visitor interfaces, accept methods, and builders.
Adapter src/PatternKit.Examples/AdapterGeneratorDemo test/PatternKit.Examples.Tests/AdapterGeneratorDemo/AdapterGeneratorDemoTests.cs External payment, logging, and clock contracts are adapted into internal abstractions.
Observer src/PatternKit.Examples/ObserverGeneratorDemo test/PatternKit.Examples.Tests/ObserverGeneratorDemo/ObserverGeneratorDemoTests.cs Notification and telemetry systems use generated event hubs and typed subscriptions.
Proxy src/PatternKit.Examples/ProxyGeneratorDemo test/PatternKit.Examples.Tests/ProxyGeneratorDemo/ProxyGeneratorDemoTests.cs Payment service calls are wrapped by generated authentication, caching, logging, retry, and timing interceptors.
Singleton src/PatternKit.Examples/SingletonGeneratorDemo test/PatternKit.Examples.Tests/SingletonGeneratorDemo/SingletonGeneratorDemoTests.cs Configuration, clocks, and service registries expose generated singleton accessors.
Template Method src/PatternKit.Examples/TemplateMethodGeneratorDemo test/PatternKit.Examples.Tests/TemplateMethodGeneratorDemo Import and order-processing workflows are generated from ordered steps and hook points.
Messaging src/PatternKit.Examples/Messaging test/PatternKit.Examples.Tests/Messaging Dispatchers, content routers, routing slips, and sagas are generated for in-process enterprise integration flows.

Corporate Application Builder

CorporateApplicationBuilderDemo is the most complete host-style generator example. It models a production startup surface where teams compose a host with environment selection, observability, messaging, background jobs, secrets, startup tasks, and module validation.

var app = await CorporateApplicationDemo.CreateBuilder()
    .ForEnvironment(CorporateEnvironment.Production)
    .EnableMessaging()
    .EnableJobs()
    .LoadSecrets()
    .AddStartupTasks()
    .RequireModules()
    .BuildAndInitializeAsync();

The generated builder keeps fluent application composition explicit. Extension methods such as EnableMessaging() and EnableJobs() remain handwritten application policy, while [GenerateBuilder] owns the repetitive builder plumbing.

DI Module And Orchestrator Factories

FactoryGeneratorExamples.cs demonstrates two factory styles:

  • [FactoryMethod] maps module names to IServiceCollection setup functions.
  • [FactoryClass] maps orchestration keys to concrete startup steps.
var provider = ServiceModuleBootstrap.Build(["metrics", "caching", "workers"]);
var orchestrator = new ApplicationOrchestrator(provider);
await orchestrator.RunAsync(["warm-cache", "start-workers"]);

This shape fits systems where module and startup order are configuration-owned, but object creation should still be compile-time generated and testable.

Generated Cross-Cutting Examples

The generator examples cover common enterprise seams:

  • Generated facades simplify billing and shipping subsystem APIs.
  • Generated proxies wrap service calls with authentication, caching, retry, logging, and timing.
  • Generated observers centralize notification and telemetry dispatch.
  • Generated mementos snapshot mutable editor/game state.
  • Generated template methods enforce workflow order while preserving hook points.
  • Generated state machines keep lifecycle transitions deterministic.

Messaging Generator Examples

Messaging examples live under src/PatternKit.Examples/Messaging:

  • DispatcherExample.cs demonstrates source-generated mediator commands, notifications, streams, and paging.
  • ContentRouterGeneratorExample.cs demonstrates generated content-based routing.
  • RoutingSlipExample.cs demonstrates generated routing-slip factories for fulfillment workflows.
  • SagaExample.cs demonstrates generated process-manager transitions over explicit state.

See Messaging Generators and Enterprise Messaging Workflow Suite for deeper routing and workflow guidance.

Validation

These examples are compiled with PatternKit.Generators as an analyzer reference, so generated code is exercised during normal builds. The examples test project verifies behavior across the supported target frameworks, and DocFX validates the crosslinks in this page.

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