diff -r 04bcd38cf8dc -r bd4e5b544473 tool/Command.cpp
--- a/tool/Command.cpp	Mon Jul 28 08:28:42 2008 +0000
+++ b/tool/Command.cpp	Mon Jul 28 08:45:28 2008 +0000
@@ -80,20 +80,32 @@
 
 /*****************************************************************************/
 
-void Command::throwInvalidUsageException(const stringstream &s)
+void Command::throwInvalidUsageException(const stringstream &s) const
 {
     throw InvalidUsageException(s);
 }
 
 /*****************************************************************************/
 
-void Command::throwCommandException(const stringstream &s)
+void Command::throwCommandException(const stringstream &s) const
 {
     throw CommandException(s);
 }
 
 /*****************************************************************************/
 
+void Command::throwSingleSlaveRequired(unsigned int size) const
+{
+    stringstream err;
+
+    err << "The slave selection matches " << size << "slaves. '"
+        << name << "' requires a single slave.";
+
+    throwInvalidUsageException(err);
+}
+
+/*****************************************************************************/
+
 Command::SlaveList Command::selectedSlaves(MasterDevice &m)
 {
     unsigned int numSlaves = m.slaveCount(), i, aliasIndex;