From c8eda79fb2c401e1e01bc3aabcfaeca161241dce Mon Sep 17 00:00:00 2001
From: Tom Henderson <tomh@tomh.org>
Date: Thu, 15 Oct 2020 11:33:48 -0700
Subject: [PATCH] mobility: (fixes #276) Make EnableAsciiAll connect in
 failsafe way

---
 src/mobility/helper/mobility-helper.cc |  4 ++--
 src/mobility/helper/mobility-helper.h  | 21 ++++++++++++---------
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/src/mobility/helper/mobility-helper.cc b/src/mobility/helper/mobility-helper.cc
index 9faca446f..aec391cce 100644
--- a/src/mobility/helper/mobility-helper.cc
+++ b/src/mobility/helper/mobility-helper.cc
@@ -236,8 +236,8 @@ MobilityHelper::EnableAscii (Ptr<OutputStreamWrapper> stream, uint32_t nodeid)
 {
   std::ostringstream oss;
   oss << "/NodeList/" << nodeid << "/$ns3::MobilityModel/CourseChange";
-  Config::ConnectWithoutContext (oss.str (), 
-                                 MakeBoundCallback (&MobilityHelper::CourseChanged, stream));
+  Config::ConnectWithoutContextFailSafe (oss.str (), 
+                                         MakeBoundCallback (&MobilityHelper::CourseChanged, stream));
 }
 void 
 MobilityHelper::EnableAscii (Ptr<OutputStreamWrapper> stream, NodeContainer n)
diff --git a/src/mobility/helper/mobility-helper.h b/src/mobility/helper/mobility-helper.h
index 63693921f..0ea23a9f3 100644
--- a/src/mobility/helper/mobility-helper.h
+++ b/src/mobility/helper/mobility-helper.h
@@ -224,26 +224,29 @@ public:
    * \param stream an output stream wrapper
    * \param nodeid the id of the node to generate ascii output for.
    *
-   * Enable ascii output on the mobility model associated to the
-   * specified nodeid and dump that to the specified stdc++ output 
-   * stream.
+   * Enable ascii output to record course changes from the mobility model
+   * associated with the specified nodeid and dump that to the specified output 
+   * stream.  If the Node does not have a MobilityModel aggregated,
+   * this method will not produce any output.
    */
   static void EnableAscii (Ptr<OutputStreamWrapper> stream, uint32_t nodeid);
   /**
    * \param stream an output stream wrapper
    * \param n node container
    *
-   * Enable ascii output on the mobility model associated each of
-   * the nodes in the input container and dump that to the 
-   * specified stdc++ output stream.
+   * Enable ascii output to record course changes from the mobility models
+   * associated to the the nodes in the input container and dump that to the 
+   * specified output stream.  Nodes that do not have a MobilityModel
+   * aggregated will not result in any output.
    */
   static void EnableAscii (Ptr<OutputStreamWrapper> stream, NodeContainer n);
   /**
    * \param stream an output stream wrapper
    *
-   * Enable ascii output on the mobility model associated
-   * every node in the system and dump that to the specified 
-   * stdc++ output stream.
+   * Enable ascii output to record course changes from the mobility models
+   * associated to every node in the system and dump that to the specified 
+   * output stream.  Nodes that do not have a MobilityModel aggregated
+   * will not result in any output.
    */
   static void EnableAsciiAll (Ptr<OutputStreamWrapper> stream);
   /**