Add the Set method to the builder (#19)

README.md

@@ -70,6 +70,15 @@ builder.Add(di.Def{
 })
 ```
 
+If you have an already built object to put in the container, you can use the `Set` shortcut:
+
+```go
+obj := &MyObject{}
+
+builder, _ := di.NewBuilder()
+builder.Set("my-object", obj)
+```
+
 
 ## Object retrieval
 

builder.go

@@ -102,6 +102,16 @@ func (b *Builder) add(def Def) error {
 	return nil
 }
 
+// Set is a shortcut to add a definition for an already built object.
+func (b *Builder) Set(name string, obj interface{}) error {
+	return b.add(Def{
+		Name: name,
+		Build: func(ctn Container) (interface{}, error) {
+			return obj, nil
+		},
+	})
+}
+
 // Build creates a Container in the most generic scope
 // with all the definitions registered in the Builder.
 func (b *Builder) Build() Container {

builder_test.go

@@ -106,6 +106,21 @@ func TestAddErrors(t *testing.T) {
 	require.Nil(t, err)
 }
 
+func TestSet(t *testing.T) {
+	b, _ := NewBuilder()
+
+	var err error
+
+	err = b.Set("", "error")
+	require.NotNil(t, err, "should not be able to set an object without a name")
+
+	err = b.Set("key", "value")
+	require.Nil(t, err)
+
+	ctn := b.Build()
+	require.Equal(t, "value", ctn.Get("key").(string))
+}
+
 func TestBuild(t *testing.T) {
 	ctn := (&Builder{}).Build()
 	require.Nil(t, ctn, "should have at least one scope to use Build")