1 files changed, 7 insertions, 6 deletions
diff --git a/libhello/libhello/hello.cxx b/libhello/libhello/hello.cxx
index 677815d..4fbd917 100644
--- a/libhello/libhello/hello.cxx
+++ b/libhello/libhello/hello.cxx
@@ -1,16 +1,17 @@
-// file: libhello/hello.cxx -*- C++ -*-
-
 #include <libhello/hello.hxx>
 
-#include <iostream>
+#include <ostream>
+#include <stdexcept>
 
 using namespace std;
 
 namespace hello
 {
-  void
-  say (const string& n)
+  void say_hello (ostream& o, const string& n)
   {
-    cout << "Hello, " << n << '!' << endl;
+    if (n.empty ())
+      throw invalid_argument ("empty name");
+
+    o << "Hello, " << n << '!' << endl;
   }
 }