Customizing builds #

Customizing the build behavior of a package is done by creating a build.yaml file, which describes your configuration.

Defining Builders to apply to dependents (similar to transformers) #

If users of your package need to apply some code generation to their package, then you can define Builders and have those applied to packages with a dependency on yours.

Exposed Builders are configured in the builders section of the build.yaml. This is a map of builder names to configuration. Each builder config may contain the following keys:

• target: The name of the target which defines contains the Builder class definition.
• import: Required. The import uri that should be used to import the library containing the Builder class. This should always be a package: uri.
• builder_factories: A List<String> which contains the names of the top-level methods in the imported library which are a function fitting the typedef Builder factoryName(List<String> args).
• build_extensions: Required. A map from input extension to the list of output extensions that may be created for that input. This must match the merged buildExtensions maps from each Builder in builder_factories.

Example builders config:

targets:
  # The target containing the builder sources.
  _my_builder: # By convention, this is private
    sources:
      - "lib/src/builder/**/*.dart"
      - "lib/builder.dart"
    dependencies:
      - "build"
      - "source_gen"
builders:
  # The actual builder config.
  my_builder:
    target: ":_my_builder"
    import: "package:my_package/builder.dart"
    builder_factories: ["myBuilder"]
    build_extensions: {".dart": [".my_package.dart"]}