Static Metaprogramming with Dart macros A quick overview of Victoria Chuks Alajemba 

Agenda ● What is static metaprogramming? ● What are Dart macros? ● Motivation behind this feature ● What can macros do? ● Applications ● Alternatives to Dart macros ● Code 

What is static metaprogramming? Static metaprogramming is a technique of writing code that will operate on other code at compile time. This “metaprogram” will take the code as its input, inspect it, and augment it. 

What are Dart macros? Dart macros is a Dart solution for static metaprogramming. It relies on Dart’s augmentation feature to create or modify code. Benefits include building in real-time, integrated directly into Dart, lives in memory, supports easy inspection and reduces boilerplate code 

Motivation behind this feature ● Boilerplate code ● Developer requests ● Diverse methodologies ● Language flexibility 

What can macros do? ● Inspect classes and their properties, methods, constructors and their parameters ● Augment existing classes by adding new methods or fields ● Create new classes ● Serve as ingredients in other macros 

Applications ● JSON serialization and deserialization, ● Data classes ● Manipulating flutter widgets ● Parsing command line arguments 

Alternatives to Dart macros ● mirrors library ● build_runner ● Code generation packages like Mason bricks ● IDE features like code snippets and plugins 

Code 

without macro with macro JSON 

without macro with macro Data class 

Before writing your macro 

@JsonCodable() 

@JsonCodable() json ^0.20.2 

generate code targets classes conditions @Singleton() singleton_macro ^0.0.2-dev.1 

linkedin.com/in/alajemba Thank you 

Useful Links & References ● Motivation behind Dart macros ● language/working/macros/feature-s pecification.md at main ● flutter.dev/go/stateful-macro ● Macros (experimental) | Dart ● Macros samples ● Json macro ● build_runner | Dart ● The fear of dart:mirrors