Added get by interface method

3 files changed, 80 insertions, 16 deletions

diff --git a/README.md b/README.md
index c20db6e..70745a9 100644
--- a/README.md
+++ b/README.md
@@ -17,12 +17,17 @@ di.Register("service id", func () (*Service, error) { /* construct service */ })
 Get dependencies by type:
 
 ```go
-services, err := di.Get[Service]()
+services, err := di.GetByType[Service]()
 ```
 
 Get dependencies by type and id:
 ```go
-service, err := di.GetById[Service]("service id")
+service, err := di.Get[Service]("service id")
+```
+
+Get dependencies by interface:
+```go
+services, err := di.GetByInterface[Worker]() // Worker is interface for many workers
 ```
 
 ### Go doc
@@ -30,8 +35,9 @@ service, err := di.GetById[Service]("service id")
 ```go
 package di // import "go.neonxp.dev/di"
 
-func Get[T any]() ([]*T, error)
-func GetById[T any](id string) (*T, error)
+func Get[T any](id string) (*T, error)
+func GetByInterface[Interface any]() ([]Interface, error)
+func GetByType[T any]() ([]*T, error)
 func Register[T any](id string, constructor func() (*T, error))
 ```
 
@@ -53,7 +59,7 @@ di.Register("serviceB", func() (*ServiceB, error) { // <- Register service B, th
 })
 
 // Do work ...
-service, err := di.GetById[ServiceB]("serviceB") // <- Get instantinated service B
+service, err := di.Get[ServiceB]("serviceB") // <- Get instantinated service B
 if err != nil {
     panic(err)
 }
diff --git a/di.go b/di.go
index b015577..8e41ee9 100644
--- a/di.go
+++ b/di.go
@@ -15,8 +15,13 @@ func init() {
 	cache = sync.Map{}
 }
 
+// Register service in di
+func Register[T any](id string, constructor func() (*T, error)) {
+	services.Store(id, constructor)
+}
+
 // Get services by type
-func Get[T any]() ([]*T, error) {
+func GetByType[T any]() ([]*T, error) {
 	var err error
 	result := []*T{}
 	services.Range(func(id, constructor any) bool {
@@ -40,13 +45,38 @@ func Get[T any]() ([]*T, error) {
 	return result, err
 }
 
-// Get service by type and id
-func GetById[T any](id string) (*T, error) {
+// Get services by interface
+func GetByInterface[Interface any]() ([]Interface, error) {
+	var err error
+	result := []Interface{}
+	services.Range(func(id, constructor any) bool {
+		if constructor, ok := constructor.(func() (Interface, error)); ok {
+			if instance, ok := cache.Load(id); ok {
+				if instance, ok := instance.(Interface); ok {
+					result = append(result, instance)
+				}
+				return true
+			}
+			instance, instErr := constructor()
+			if instErr != nil {
+				err = instErr
+				return false
+			}
+			cache.Store(id, instance)
+			result = append(result, instance)
+		}
+		return true
+	})
+	return result, err
+}
+
+// Get service by id and type
+func Get[T any](id string) (*T, error) {
 	if instance, ok := cache.Load(id); ok {
 		if instance, ok := instance.(*T); ok {
 			return instance, nil
 		}
-		return nil, fmt.Errorf("invalid type %t for service %s", instance, id)
+		return nil, fmt.Errorf("invalid type for service %s (%t)", id, instance)
 	}
 	if constructor, ok := services.Load(id); ok {
 		if constructor, ok := constructor.(func() (*T, error)); ok {
@@ -57,11 +87,7 @@ func GetById[T any](id string) (*T, error) {
 			cache.Store(id, instance)
 			return instance, nil
 		}
-		return nil, fmt.Errorf("invalid type %t for service %s", constructor, id)
+		return nil, fmt.Errorf("invalid constructor")
 	}
 	return nil, fmt.Errorf("unknown service %s", id)
 }
-
-func Register[T any](id string, constructor func() (*T, error)) {
-	services.Store(id, constructor)
-}
diff --git a/di_test.go b/di_test.go
index cd0eb23..a67a82e 100644
--- a/di_test.go
+++ b/di_test.go
@@ -11,7 +11,7 @@ func ExampleGet() {
 		return &ServiceA{}, nil
 	})
 	di.Register("serviceB", func() (*ServiceB, error) { // <- Register service B, that depends from service A
-		serviceA, err := di.Get[ServiceA]() // <- Get dependency from container by type
+		serviceA, err := di.GetByType[ServiceA]() // <- Get dependency from container by type
 		if err != nil {
 			return nil, err
 		}
@@ -22,13 +22,29 @@ func ExampleGet() {
 	})
 
 	// Do work...
-	service, err := di.GetById[ServiceB]("serviceB") // <- Get instantinated service B
+	service, err := di.Get[ServiceB]("serviceB") // <- Get instantinated service B
 	if err != nil {
 		panic(err)
 	}
 	service.DoStuff() // Output: Hello, world!
 }
 
+func ExampleGet_interface() {
+	di.Register("worker1", func() (*Worker1, error) {
+		return &Worker1{}, nil
+	})
+	di.Register("worker2", func() (*Worker2, error) {
+		return &Worker2{}, nil
+	})
+	workers, err := di.GetByInterface[Worker]()
+	if err != nil {
+		panic(err)
+	}
+	for _, w := range workers {
+		w.Do()
+	}
+}
+
 type ServiceA struct{}
 
 func (d *ServiceA) DoStuff() {
@@ -42,3 +58,19 @@ type ServiceB struct {
 func (d *ServiceB) DoStuff() {
 	d.ServiceA.DoStuff()
 }
+
+type Worker interface {
+	Do()
+}
+
+type Worker1 struct{}
+
+func (w *Worker1) Do() {
+	fmt.Println("Worker 1 says hello")
+}
+
+type Worker2 struct{}
+
+func (w *Worker2) Do() {
+	fmt.Println("Worker 2 says hello")
+}