diff -r 0e4f009eab8b -r 67188bd752db io_helper.cc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/io_helper.cc	Mon Jul 07 08:10:39 2008 -0500
@@ -0,0 +1,34 @@
+#include "io_helper.h"
+
+namespace lemon {
+  void xml(XmlIo &x, MapValue::Type& v)
+  {
+    if(x.write()) {
+      switch (v)
+      {
+        case MapValue::NUMERIC:
+          { x("type", std::string("numeric")); }
+          break;
+        case MapValue::STRING:
+          { x("type", std::string("string")); }
+          break;
+      }
+    }
+    else {
+      std::string type;
+      { x("type", type); }
+      if (type == "numeric")
+      {
+        v = MapValue::NUMERIC;
+      }
+      else if (type == "string")
+      {
+        v = MapValue::STRING;
+      }
+      else
+      {
+        throw DataFormatError("Bad format");
+      }
+    }
+  }
+};