Run capability funciton using argmappers

builtin/myplugin/host/cap/write_hello.go

@@ -1,8 +1,16 @@
 package cap
 
-import "io/ioutil"
+import (
+	"io/ioutil"
 
-func WriteHello() {
+	"github.com/hashicorp/vagrant-plugin-sdk/terminal"
+)
+
+func WriteHelloFunc() interface{} {
+	return WriteHello
+}
+
+func WriteHello(trm terminal.UI) {
 	data := []byte("hello\ngo\n")
 	ioutil.WriteFile("/tmp/dat1", data, 0644)
 }

builtin/myplugin/host/osx.go

@@ -23,14 +23,14 @@ func (h *OSXHost) DetectFunc() interface{} {
 }
 
 func (h *OSXHost) Detect() bool {
+	h.InitializeCapabilities()
 	return true
 }
 
 func (h *OSXHost) InitializeCapabilities() {
-	h.RegisterCapability("write_hello", cap.WriteHello)
+	h.RegisterCapability("write_hello", cap.WriteHelloFunc)
 }
 
 var (
 	_ component.Host = (*OSXHost)(nil)
-	_ sdkcore.Host   = (*OSXHost)(nil)
 )