This is a lightweight Inversion of Control (Dependency Injection) framework for Go. It's very convenient to register concrete value, singleton or transient prototype into the container, and resolve the value somewhere else with all dependencies automatically injected.
Each registry will return its name as identifier, which is composed of type's package path and name.
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How to get the name
ioc.NameOf(v)will returns v's name -
Concrete value's name
ioc.NameOf(&Rectangle{})isgithub.com/gopub/ioc_test/*Rectangle
ioc.NameOf(Rectangle{})isgithub.com/gopub/ioc_test/Rectangle -
Interface's name
Must pass pointer to interface in order to get its name
Error:
ioc.NameOf(Shape(nil))isnil
Correct:
ioc.NameOf((*Shape)(nil))isgithub.com/gopub/ioc_test/Shape -
Alias for name
name := ioc.RegisterSingleton(&Rectangle{}) //Add "MyRectangle" as alias for &Rectangle{} ioc.RegisterAliases(name, "MyRectangle") //r1 and r2 is equal r1 := ioc.Resolve(name) r2 := ioc.Resolve("MyRectangle")
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Concrete value
//register ioc.RegisterValue("key", "123456") ioc.RegisterValue("db", db) //fetch value in somewhere else key := ioc.Resolve("key").(string) db := ioc.Resolve("db").(*sql.DB) -
Singleton prototype
RegisterSingleton ensures only one value will be created no matter how many times it is resolved.
//register ioc.RegisterSingleton(&LoginService{}) //fetch value in somewhere else //s1 is the same with s2 s1 := ioc.Resolve(&LoginService{}).(*LoginService) s2 := ioc.Resolve(&LoginService{}).(*LoginService) -
Transient prototype
Use RegisterTransient to register a type of which many values will be created.ioc.RegisterTransient(&Rectangle{}) //r1 and r2 are different values. r1 := ioc.Resolve(&Rectangle{}).(*Rectangle) r2 := ioc.Resolve(&Rectangle{}).(*Rectangle) -
Prototype for interface It's very common to bind a concrete type to an interface type. To support this scenario, register interface's name as an alias of concrete type's name.
//Rectange implements Shape interface rectName := ioc.RegisterSingleton(&Rectangle{}) shapeName := ioc.NameOf((*Shape)(nil)) ioc.RegisterAliases(rectName, shapeName) //Create &Rectange{} as Shape s := ioc.Resolve(shapeName).(Shape) fmt.Print(s.Area()) -
Timing
The type and its dependencies must be registered before resolve. It's good time to do registry operations before main function executes.- In package's init() function
func init() { ioc.RegisterSingleton(&LoginService{}) }- Declare global variable to trigger registry operation
//Declare just ahead of type definition var _ = ioc.RegisterSingleton(&LoginService{}) type LoginService struct { }
Use tag inject to declare dependencies. Field name must start with an uppercase character in case it will cause unexported panic error.
var _ = ioc.RegisterSingleton(&LoginController{})
type LoginController struct {
//depend value with name: page_title
PageTitle string `inject:"page_title"`
//depend value with name: ioc.NameOf((*LoginService)(nil))
LoginService *LoginService `inject:""`
}
//somewhere else
controller := ioc.Resolve(&LoginController{}).(*LoginController)
//...