mix_generator

mix_generator

Code generator for the Mix styling framework. Processes mix_annotations to generate boilerplate code for Spec, Styler, and Mix classes.

Installation

flutter pub add mix
flutter pub add mix_annotations
flutter pub add --dev mix_generator
flutter pub add --dev build_runner

Or in pubspec.yaml:

dependencies:
  mix: ^2.0.0
  mix_annotations: ^2.0.0

dev_dependencies:
  build_runner: ^2.4.0
  mix_generator: ^2.0.0

What It Generates

From @MixableSpec — Spec mixin

Generates a _$<Name> mixin for immutable Spec classes with:

• copyWith() — create modified copies
• == / hashCode — value equality
• lerp() — smooth interpolation between specs

import 'package:mix/mix.dart';
import 'package:mix_annotations/mix_annotations.dart';

part 'box_spec.g.dart';

@MixableSpec()
final class BoxSpec extends Spec<BoxSpec> with _$BoxSpec {
  final Color? color;
  final double? width;
  final double? height;
  final AlignmentGeometry? alignment;

  const BoxSpec({this.color, this.width, this.height, this.alignment});
}

From @MixableStyler — Styler mixin

Generates a _$<Name>Mixin for mutable Styler classes with:

• Setter methods for each $-prefixed field
• merge() — combine styles
• resolve() — resolve to the corresponding Spec
• debugFillProperties() — diagnostics support
• props — equality comparison
• call() — widget creation

part 'box_styler.g.dart';

@MixableStyler()
class BoxStyler extends Style<BoxSpec>
    with Diagnosticable, _$BoxStylerMixin {
  final Prop<Color>? $color;
  final Prop<double>? $width;
  final Prop<double>? $height;
  final Prop<AlignmentGeometry>? $alignment;

  // ...
}

From @Mixable — Mix mixin

Generates a _$<Name>Mixin for compound property types with:

• merge() — combine mix instances
• resolve() — resolve to the target type
• props — equality comparison
• debugFillProperties() — diagnostics support

part 'box_constraints_mix.g.dart';

@Mixable()
final class BoxConstraintsMix extends ConstraintsMix<BoxConstraints>
    with DefaultValue<BoxConstraints>, Diagnosticable, _$BoxConstraintsMixMixin {
  final Prop<double>? $minWidth;
  final Prop<double>? $maxWidth;
  final Prop<double>? $minHeight;
  final Prop<double>? $maxHeight;

  // ...
}

Field-level control with @MixableField

// Skip setter generation
@MixableField(ignoreSetter: true)
final Prop<Matrix4>? $transform;

// Override the setter parameter type
@MixableField(setterType: List<Shadow>)
final Prop<List<Shadow>>? $shadows;

Running the Generator

dart run build_runner build

Or within the Mix monorepo:

melos run gen:build

Generated files use the .g.dart extension and should be committed to version control.

Debugging

VS Code

1. Set breakpoints in the generator source files under lib/src/.
2. Select the "Debug build_runner" launch configuration.
3. Press F5.

Manual

dart --enable-vm-service=8888 --pause-isolates-on-start run build_runner build --verbose

Then connect your debugger to localhost:8888.

Learn More

• Mix documentation
• mix — Core framework
• mix_annotations — Annotation definitions
• GitHub repository