wire

README

wire

Wire is runtime depedency injection/wiring for golang. It's designed to be strict to avoid your go application running without proper dependency injected.

Features:

• Strictly validates dependency and prevents missing or ambiguous dependency.
• Check againts possible forgotten wire tag.
• Easily connect and resolve object anywhere.
• Annotates ambiguous interface type using connection name or implementation name.

Install

go get github.com/Fs02/wire

Example

package wire_test

import (
	"fmt"

	"github.com/Fs02/wire"
)

type Listener struct{}

func (listener Listener) Next() string {
	return "system"
}

type Printer interface {
	Exec(string) error
}

type SystemPrint struct {
	App string `wire:""`
}

func (systemPrint SystemPrint) Exec(msg string) error {
	fmt.Println("[" + systemPrint.App + "] System: " + msg)
	return nil
}

type UserPrint struct {
	App    string `wire:""`
	Target string
}

func (userPrint UserPrint) Exec(msg string) error {
	fmt.Println("[" + userPrint.App + "]" + userPrint.Target + ": " + msg)
	return nil
}

type Service struct {
	// Each of `wire`` tag below indicate fields to be wired with apporpriate component.
	// value inside `wire` tag indicate the name of the component and optionally it's type.
	// `wire` with empty value will be wired with default value (named using empty string).
	// Ambiguous field can be resolved by adding it's type, name or both (separated using comma) to the `wire` tag.
	// Don't worry if you forgot to add wire tag to an interface or a pointer, wire will warn you if any nil field are found.
	// To ignore wiring on specific field, you can use add `wire:"-"`.
	Listener     Listener `wire:""`
	SystemPrint  Printer  `wire:",SystemPrint"`
	FooUserPrint Printer  `wire:"foo"`
	BooUserPrint Printer  `wire:"boo,UserPrint"`
}

func (service Service) Update() error {
	switch service.Listener.Next() {
	case "system":
		return service.SystemPrint.Exec("hello from system")
	case "user-foo":
		return service.FooUserPrint.Exec("hello from foo")
	case "user-boo":
		return service.BooUserPrint.Exec("hello from boo")
	default:
		return nil
	}
}

func init() {
	// add components to be wired by the library.
	// wire all components only once and as early as possible.
	wire.Connect("CoolApp")
	wire.Connect(Listener{})                       // we don't need to pass by reference here, since it doesn't require any wiring.
	wire.Connect(&SystemPrint{})                   // we need to pass by reference it to allow wiring, wire will panic if we pass by value.
	wire.Connect(&UserPrint{Target: "foo"}, "foo") // wire a UserPrint named by "foo".
	wire.Connect(&UserPrint{Target: "boo"}, "boo") // wire a UserPrint named by "boo", wire will panic if there's duplicate components detected.
	wire.Connect(&Service{})

	// Apply wiring
	wire.Apply()
}

func Example() {
	// Resolve a service component to be used later.
	var service Service
	wire.Resolve(&service)

	service.Update()
	// Output: [CoolApp] System: hello from system
}

License

Released under the MIT License

Documentation

Overview

Package wire is runtime depedency injection/wiring for golang. It's designed to be strict to avoid your go application running without proper dependency injected.

Example

package main

import (
	"fmt"

	"github.com/Fs02/wire"
)

type Listener struct{}

func (listener Listener) Next() string {
	return "system"
}

type Printer interface {
	Exec(string) error
}

type SystemPrint struct {
	App string `wire:""`
}

func (systemPrint SystemPrint) Exec(msg string) error {
	fmt.Println("[" + systemPrint.App + "] System: " + msg)
	return nil
}

type UserPrint struct {
	App    string `wire:""`
	Target string
}

func (userPrint UserPrint) Exec(msg string) error {
	fmt.Println("[" + userPrint.App + "]" + userPrint.Target + ": " + msg)
	return nil
}

type Service struct {
	// Each of `wire`` tag below indicate fields to be wired with apporpriate component.
	// value inside `wire` tag indicate the name of the component and optionally it's type.
	// `wire` with empty value will be wired with default value (named using empty string).
	// Ambiguous field can be resolved by adding it's type, name or both (separated using comma) to the `wire` tag.
	// Don't worry if you forgot to add wire tag to an interface or a pointer, wire will warn you if any nil field are found.
	// To ignore wiring on specific field, you can use add `wire:"-"`.
	Listener     Listener `wire:""`
	SystemPrint  Printer  `wire:",SystemPrint"`
	FooUserPrint Printer  `wire:"foo"`
	BooUserPrint Printer  `wire:"boo,UserPrint"`
}

func (service Service) Update() error {
	switch service.Listener.Next() {
	case "system":
		return service.SystemPrint.Exec("hello from system")
	case "user-foo":
		return service.FooUserPrint.Exec("hello from foo")
	case "user-boo":
		return service.BooUserPrint.Exec("hello from boo")
	default:
		return nil
	}
}

func init() {
	// add components to be wired by the library.
	// wire all components only once and as early as possible.
	wire.Connect("CoolApp")
	wire.Connect(Listener{})                       // we don't need to pass by reference here, since it doesn't require any wiring.
	wire.Connect(&SystemPrint{})                   // we need to pass by reference it to allow wiring, wire will panic if we pass by value.
	wire.Connect(&UserPrint{Target: "foo"}, "foo") // wire a UserPrint named by "foo".
	wire.Connect(&UserPrint{Target: "boo"}, "boo") // wire a UserPrint named by "boo", wire will panic if there's duplicate components detected.
	wire.Connect(&Service{})

	// Apply wiring
	wire.Apply()
}

func main() {
	// Resolve a service component to be used later.
	var service Service
	wire.Resolve(&service)

	service.Update()
}

Output:

[CoolApp] System: hello from system

Index

• func Apply()
• func Connect(val interface{}, name ...string)
• func Resolve(out interface{}, name ...string)
• type Container
  • func New() Container
  • func (container Container) Apply()
  • func (container Container) Connect(val interface{}, id ...string)
  • func (container Container) Resolve(out interface{}, id ...string)

Examples

• Package

Functions

func Apply

func Apply()

Apply wiring to all components.

This will panic if:

1. There are missing component.
2. Ambiguous field found, usually field with type interface that can satisfy more than one component.

func Connect

func Connect(val interface{}, name ...string)

Connect a component, optionally identified by name.

This will panic if:

1. Duplicate component found.
2. Possible forgotten `wire` tag found on pointer and interface field.
3. Component that need wiring is passed using value.

func Resolve

func Resolve(out interface{}, name ...string)

Resolve a component optionally identified by name.

This should be called only after wiring applied. Resolving component multiple times should be avoided, consider caching the component if you need. For example, if you are running a web server, Resolve should only be done before the server start listening for request.

This will panic if no matching component is found.

Types

type Container

type Container struct {
	// contains filtered or unexported fields
}

Container provides an isolated container for DI.

func New

func New() Container

New create new isolated DI container.

func (Container) Apply

func (container Container) Apply()

Apply wiring to all components.

func (Container) Connect

func (container Container) Connect(val interface{}, id ...string)

Connect a component, optionally identified by id.

func (Container) Resolve

func (container Container) Resolve(out interface{}, id ...string)

Resolve a component with identified id.