autowire

README

autowire

Compile-time dependency injection for Go using annotations.

Installation

go install github.com/eloonstra/autowire@latest

Usage

Run directly:

autowire --out ./cmd --scan ./internal --scan ./pkg

or via go generate (for example in cmd/main.go):

//go:generate autowire --scan ../internal --scan ../pkg

Annotations

//autowire:provide
func NewConfig() *Config { ... }

//autowire:provide
func NewDatabase(cfg *Config) (*Database, error) { ... }

//autowire:provide
type Server struct {
    Config *Config // injected (exported fields only)
}

//autowire:invoke
func SetupRoutes(svc *UserService) error { ... }

• //autowire:provide: registers a single type as injectable (functions or structs)
• //autowire:invoke: calls a function during initialization for side effects

Functions can optionally return an error.

Interface Binding

Bind a provider to an interface instead of its concrete type:

//autowire:provide Reader
func NewFileReader() *FileReader { ... }

For interfaces from other packages, import the package and use the package alias:

import "io"

var _ io.Writer = (*BufferedWriter)(nil) // compile-time check

//autowire:provide io.Writer
func NewBufferedWriter() *BufferedWriter { ... }

Adding var _ interfaces.Interface = (*Implementation)(nil) is recommended. it verifies at compile time that your type implements the interface and prevents "imported and not used" errors.

• InterfaceName: interface in same package
• package.InterfaceName: imported interface (requires import)

Generated Output

Generates app_gen.go with an App struct containing all providers and an InitializeApp() function that wires everything in dependency order:

func main() {
    app, err := InitializeApp()
    if err != nil {
        panic(err)
    }
	
    app.Server.Start()
}

Comparison

	autowire	wire (archived)	do	Fx
Compile-time safe	✓	✓	✓
Code generation	✓	✓
No manual wiring	✓
Struct injection	✓
Zero runtime cost	✓	✓
Cycle detection	✓	✓	✓	✓
Interface binding	✓	✓	✓	✓
Lifecycle hooks			✓	✓
Named dependencies	soon™	✓	✓	✓

• wire: Google's compile-time DI, requires manual provider sets (archived)
• do: Lightweight runtime DI container with generics
• Fx: Uber's application framework with lifecycle management

License

MIT