Merge pull request #18 from codegangsta/JMS-Implementors

inject will now inject interface implementors as dependencies

inject.go

@@ -157,10 +157,29 @@ func (i *injector) Set(typ reflect.Type, val reflect.Value) TypeMapper {
 
 func (i *injector) Get(t reflect.Type) reflect.Value {
 	val := i.values[t]
+
+	if val.IsValid() {
+		return val
+	}
+
+	// no concrete types found, try to find implementors
+	// if t is an interface
+	if t.Kind() == reflect.Interface {
+		for k, v := range i.values {
+			if k.Implements(t) {
+				val = v
+				break
+			}
+		}
+	}
+
+	// Still no type found, try to look it up on the parent
 	if !val.IsValid() && i.parent != nil {
 		val = i.parent.Get(t)
 	}
+
 	return val
+
 }
 
 func (i *injector) SetParent(parent Injector) {

inject_test.go

@@ -1,6 +1,7 @@
 package inject_test
 
 import (
+	"fmt"
 	"github.com/codegangsta/inject"
 	"reflect"
 	"testing"
@@ -15,6 +16,14 @@ type TestStruct struct {
 	Dep3 string
 }
 
+type Greeter struct {
+	Name string
+}
+
+func (g *Greeter) String() string {
+	return "Hello, My name is" + g.Name
+}
+
 /* Test Helpers */
 func expect(t *testing.T, a interface{}, b interface{}) {
 	if a != b {
@@ -140,3 +149,11 @@ func Test_InjectorSetParent(t *testing.T) {
 
 	expect(t, injector2.Get(inject.InterfaceOf((*SpecialString)(nil))).IsValid(), true)
 }
+
+func TestInjectImplementors(t *testing.T) {
+	injector := inject.New()
+	g := &Greeter{"Jeremy"}
+	injector.Map(g)
+
+	expect(t, injector.Get(inject.InterfaceOf((*fmt.Stringer)(nil))).IsValid(), true)
+}