bindings: (fixes #796) Gracefully exit when bindings are unavailable

examples/realtime/realtime-udp-echo.py

@@ -23,7 +23,14 @@
 # - DropTail queues
 # - Tracing of queues and packet receptions to file "udp-echo.tr"
 
-from ns import ns
+try:
+    from ns import ns
+except ModuleNotFoundError:
+    raise SystemExit(
+        "Error: ns3 Python module not found;"
+        " Python bindings may not be enabled"
+        " or your PYTHONPATH might not be properly configured"
+    )
 
 def main(argv):
   #

examples/routing/simple-routing-ping6.py

@@ -27,7 +27,14 @@
 #                router
 #
 
-from ns import ns
+try:
+    from ns import ns
+except ModuleNotFoundError:
+    raise SystemExit(
+        "Error: ns3 Python module not found;"
+        " Python bindings may not be enabled"
+        " or your PYTHONPATH might not be properly configured"
+    )
 
 
 def main(argv):

examples/tutorial/first.py

@@ -13,7 +13,14 @@
 #  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 #  */
 
-from ns import ns
+try:
+    from ns import ns
+except ModuleNotFoundError:
+    raise SystemExit(
+        "Error: ns3 Python module not found;"
+        " Python bindings may not be enabled"
+        " or your PYTHONPATH might not be properly configured"
+    )
 
 # // Default Network Topology
 # //

examples/tutorial/second.py

@@ -16,7 +16,14 @@
 #  * Ported to Python by Mohit P. Tahiliani
 #  */
 
-from ns import ns
+try:
+    from ns import ns
+except ModuleNotFoundError:
+    raise SystemExit(
+        "Error: ns3 Python module not found;"
+        " Python bindings may not be enabled"
+        " or your PYTHONPATH might not be properly configured"
+    )
 import sys
 
 # // Default Network Topology

examples/tutorial/third.py

@@ -16,7 +16,14 @@
 #  * Ported to Python by Mohit P. Tahiliani
 #  */
 
-from ns import ns
+try:
+    from ns import ns
+except ModuleNotFoundError:
+    raise SystemExit(
+        "Error: ns3 Python module not found;"
+        " Python bindings may not be enabled"
+        " or your PYTHONPATH might not be properly configured"
+    )
 import sys
 
 # // Default Network Topology

examples/wireless/mixed-wired-wireless.py

@@ -51,7 +51,14 @@
 #           +----------------+                       +----------------+
 #
 
-from ns import ns
+try:
+    from ns import ns
+except ModuleNotFoundError:
+    raise SystemExit(
+        "Error: ns3 Python module not found;"
+        " Python bindings may not be enabled"
+        " or your PYTHONPATH might not be properly configured"
+    )
 
 # #
 # #  This function will be used below as a trace sink

examples/wireless/wifi-ap.py

@@ -22,7 +22,14 @@
 
 import sys
 
-from ns import ns
+try:
+    from ns import ns
+except ModuleNotFoundError:
+    raise SystemExit(
+        "Error: ns3 Python module not found;"
+        " Python bindings may not be enabled"
+        " or your PYTHONPATH might not be properly configured"
+    )
 
 # void
 # DevTxTrace (std::string context, Ptr<const Packet> p, Mac48Address address)