Remove unused field

arrgh.go

@@ -27,10 +27,9 @@ import (
 
 // Session holds OpenCPU session connection information.
 type Session struct {
-	cmd     *exec.Cmd
-	host    *url.URL
-	control io.Writer
-	root    string
+	cmd  *exec.Cmd
+	host *url.URL
+	root string
 }
 
 // NewLocalSession starts an R instance using the executable in the given
@@ -64,7 +63,7 @@ func NewLocalSession(path, root string, port int, timeout time.Duration) (*Sessi
 	}
 	sess.host.Path = pth.Join(sess.host.Path, root)
 	sess.root = pth.Join("/", root)
-	sess.control, err = sess.cmd.StdinPipe()
+	control, err := sess.cmd.StdinPipe()
 	if err != nil {
 		panic(err)
 	}
@@ -84,7 +83,7 @@ if (parse_version(as.character(packageVersion("opencpu"))) < "2.0.0") {
 	ocpu_start_server(port=%[1]d)
 }
 `
-	fmt.Fprintf(sess.control, startServer, port)
+	fmt.Fprintf(control, startServer, port)
 
 	runtime.SetFinalizer(&sess, func(s *Session) { s.Close() })
 
@@ -112,7 +111,6 @@ func (s *Session) Close() error {
 		return nil
 	}
 	s.host = nil
-	s.control = nil
 	return s.cmd.Process.Kill()
 }