Dart Code Generation#

A comprehensive reference for building Dart code generators using build_runner, source_gen, and the Dart analyzer.

What's Inside#

Core#

• Build System — The build package interfaces: Builder, BuildStep, AssetId, Resolver, and more.
• build.yaml Reference — Full configuration reference for declaring builders, targets, and options.
• Package Structure — How to organize a generator package with proper exports and dependencies.

Code Generation#

• Analyzer API — Navigate the Dart element model: LibraryElement, ClassElement, DartType, and visitors.
• source_gen — Higher-level abstractions: GeneratorForAnnotation, LibraryGenerator, and output formatting.
• Approaches — Side-by-side comparison of raw Builder, source_gen, and annotation-driven patterns.
• Annotations — Defining, reading, and validating custom annotations with ConstantReader.

Practical#

• Complete Recipes — End-to-end examples: JSON serializer, route generator, DI container, and more.
• Testing — Unit and integration testing strategies for generators.
• Debugging — Troubleshooting build failures, attach a debugger, and common pitfalls.