Modernize Python 2 code to get ready for Python 3

Author: cclauss

.travis.yml

@@ -6,7 +6,7 @@ env:
     - SITL_RATE=200
 
 python:
-  - 2.7.13
+  - 2.7
   - 3.6
 
 before_install:
@@ -17,10 +17,10 @@ install:
   - pip install flake8
 
 before_script:
-  # --exit-zero means that flake8 will not stop the build
-  # 127 characters is the width of a GitHub editor
-  - flake8 . --count --exit-zero  --max-line-length=127 --select=E999 --statistics  # syntax errors
-  - flake8 . --count --exit-zero  --max-line-length=127 --statistics
+  # stop the build if there are Python syntax errors or undefined names
+  - flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics
+  # exit-zero treats all errors as warnings.  The GitHub editor is 127 chars wide
+  - flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
 
 script:
   - nosetests --debug=nose,nose.importer --debug-log=nose_debug -svx dronekit.test.unit
@@ -41,7 +41,6 @@ notifications:
 matrix:
   allow_failures:
   - python: 3.6
-  fast_finish: true
 
 branches:
   only:

examples/channel_overrides/channel_overrides.py

@@ -17,6 +17,7 @@
 
 Full documentation is provided at http://python.dronekit.io/examples/channel_overrides.html
 """
+from __future__ import print_function
 from dronekit import connect
 
 
@@ -39,61 +40,61 @@
 
 
 # Connect to the Vehicle
-print 'Connecting to vehicle on: %s' % connection_string
+print('Connecting to vehicle on: %s' % connection_string)
 vehicle = connect(connection_string, wait_ready=True)
 
 # Get all original channel values (before override)
-print "Channel values from RC Tx:", vehicle.channels
+print("Channel values from RC Tx:", vehicle.channels)
 
 # Access channels individually
-print "Read channels individually:"
-print " Ch1: %s" % vehicle.channels['1']
-print " Ch2: %s" % vehicle.channels['2']
-print " Ch3: %s" % vehicle.channels['3']
-print " Ch4: %s" % vehicle.channels['4']
-print " Ch5: %s" % vehicle.channels['5']
-print " Ch6: %s" % vehicle.channels['6']
-print " Ch7: %s" % vehicle.channels['7']
-print " Ch8: %s" % vehicle.channels['8']
-print "Number of channels: %s" % len(vehicle.channels)
+print("Read channels individually:")
+print(" Ch1: %s" % vehicle.channels['1'])
+print(" Ch2: %s" % vehicle.channels['2'])
+print(" Ch3: %s" % vehicle.channels['3'])
+print(" Ch4: %s" % vehicle.channels['4'])
+print(" Ch5: %s" % vehicle.channels['5'])
+print(" Ch6: %s" % vehicle.channels['6'])
+print(" Ch7: %s" % vehicle.channels['7'])
+print(" Ch8: %s" % vehicle.channels['8'])
+print("Number of channels: %s" % len(vehicle.channels))
 
 
 # Override channels
-print "\nChannel overrides: %s" % vehicle.channels.overrides
+print("\nChannel overrides: %s" % vehicle.channels.overrides)
 
-print "Set Ch2 override to 200 (indexing syntax)"
+print("Set Ch2 override to 200 (indexing syntax)")
 vehicle.channels.overrides['2'] = 200
-print " Channel overrides: %s" % vehicle.channels.overrides
-print " Ch2 override: %s" % vehicle.channels.overrides['2']
+print(" Channel overrides: %s" % vehicle.channels.overrides)
+print(" Ch2 override: %s" % vehicle.channels.overrides['2'])
 
-print "Set Ch3 override to 300 (dictionary syntax)"
+print("Set Ch3 override to 300 (dictionary syntax)")
 vehicle.channels.overrides = {'3':300}
-print " Channel overrides: %s" % vehicle.channels.overrides
+print(" Channel overrides: %s" % vehicle.channels.overrides)
 
-print "Set Ch1-Ch8 overrides to 110-810 respectively"
+print("Set Ch1-Ch8 overrides to 110-810 respectively")
 vehicle.channels.overrides = {'1': 110, '2': 210,'3': 310,'4':4100, '5':510,'6':610,'7':710,'8':810}
-print " Channel overrides: %s" % vehicle.channels.overrides 
+print(" Channel overrides: %s" % vehicle.channels.overrides) 
 
 
 # Clear override by setting channels to None
-print "\nCancel Ch2 override (indexing syntax)"
+print("\nCancel Ch2 override (indexing syntax)")
 vehicle.channels.overrides['2'] = None
-print " Channel overrides: %s" % vehicle.channels.overrides 
+print(" Channel overrides: %s" % vehicle.channels.overrides) 
 
-print "Clear Ch3 override (del syntax)"
+print("Clear Ch3 override (del syntax)")
 del vehicle.channels.overrides['3']
-print " Channel overrides: %s" % vehicle.channels.overrides 
+print(" Channel overrides: %s" % vehicle.channels.overrides) 
 
-print "Clear Ch5, Ch6 override and set channel 3 to 500 (dictionary syntax)"
+print("Clear Ch5, Ch6 override and set channel 3 to 500 (dictionary syntax)")
 vehicle.channels.overrides = {'5':None, '6':None,'3':500}
-print " Channel overrides: %s" % vehicle.channels.overrides 
+print(" Channel overrides: %s" % vehicle.channels.overrides) 
 
-print "Clear all overrides"
+print("Clear all overrides")
 vehicle.channels.overrides = {}
-print " Channel overrides: %s" % vehicle.channels.overrides 
+print(" Channel overrides: %s" % vehicle.channels.overrides) 
 
 #Close vehicle object before exiting script
-print "\nClose vehicle object"
+print("\nClose vehicle object")
 vehicle.close()
 
 # Shut down simulator if it was started.

examples/create_attribute/create_attribute.py

@@ -14,6 +14,7 @@
 
 Full documentation is provided at http://python.dronekit.io/examples/create_attribute.html
 """
+from __future__ import print_function
 
 from dronekit import connect, Vehicle
 from my_vehicle import MyVehicle #Our custom vehicle class
@@ -40,25 +41,25 @@
 
 
 # Connect to the Vehicle
-print 'Connecting to vehicle on: %s' % connection_string
+print('Connecting to vehicle on: %s' % connection_string)
 vehicle = connect(connection_string, wait_ready=True, vehicle_class=MyVehicle)
 
 # Add observer for the custom attribute
 
 def raw_imu_callback(self, attr_name, value):
     # attr_name == 'raw_imu'
     # value == vehicle.raw_imu
-    print value
+    print(value)
 
 vehicle.add_attribute_listener('raw_imu', raw_imu_callback)
 
-print 'Display RAW_IMU messages for 5 seconds and then exit.'
+print('Display RAW_IMU messages for 5 seconds and then exit.')
 time.sleep(5)
 
 #The message listener can be unset using ``vehicle.remove_message_listener``
 
 #Close vehicle object before exiting script
-print "Close vehicle object"
+print("Close vehicle object")
 vehicle.close()
 
 # Shut down simulator if it was started.

examples/flight_replay/flight_replay.py

@@ -10,6 +10,7 @@
 
 Full documentation is provided at http://python.dronekit.io/examples/flight_replay.html
 """
+from __future__ import print_function
 
 from dronekit import connect, Command, VehicleMode, LocationGlobalRelative
 from pymavlink import mavutil
@@ -107,7 +108,7 @@ def arm_and_takeoff(aTargetAltitude):
 
     # Don't try to arm until autopilot is ready
     while not vehicle.is_armable:
-        print " Waiting for vehicle to initialise..."
+        print(" Waiting for vehicle to initialise...")
         time.sleep(1)
 
     # Set mode to GUIDED for arming and takeoff:
@@ -118,10 +119,10 @@ def arm_and_takeoff(aTargetAltitude):
     # Confirm vehicle armed before attempting to take off
     while not vehicle.armed:
         vehicle.armed = True
-        print " Waiting for arming..."
+        print(" Waiting for arming...")
         time.sleep(1)
 
-    print " Taking off!"
+    print(" Taking off!")
     vehicle.simple_takeoff(aTargetAltitude) # Take off to target altitude
 
     # Wait until the vehicle reaches a safe height 
@@ -130,16 +131,16 @@ def arm_and_takeoff(aTargetAltitude):
         requiredAlt = aTargetAltitude*0.95
         #Break and return from function just below target altitude.        
         if vehicle.location.global_relative_frame.alt>=requiredAlt: 
-            print " Reached target altitude of ~%f" % (aTargetAltitude)
+            print(" Reached target altitude of ~%f" % (aTargetAltitude))
             break
-        print " Altitude: %f < %f" % (vehicle.location.global_relative_frame.alt,
-                                      requiredAlt)
+        print(" Altitude: %f < %f" % (vehicle.location.global_relative_frame.alt,
+                                      requiredAlt))
         time.sleep(1)
 
 
 print("Generating waypoints from tlog...")
 messages = position_messages_from_tlog(args.tlog)
-print " Generated %d waypoints from tlog" % len(messages)
+print(" Generated %d waypoints from tlog" % len(messages))
 if len(messages) == 0:
     print("No position messages found in log")
     exit(0)
@@ -157,7 +158,7 @@ def arm_and_takeoff(aTargetAltitude):
     connection_string = sitl.connection_string()
 
 # Connect to the Vehicle
-print 'Connecting to vehicle on: %s' % connection_string
+print('Connecting to vehicle on: %s' % connection_string)
 vehicle = connect(connection_string, wait_ready=True)
 
 
@@ -168,8 +169,7 @@ def arm_and_takeoff(aTargetAltitude):
 
 cmds = vehicle.commands
 cmds.clear()
-for i in xrange(0, len(messages)):
-    pt = messages[i]
+for pt in messages:
     #print "Point: %d %d" % (pt.lat, pt.lon,)
     lat = pt.lat
     lon = pt.lon
@@ -189,11 +189,11 @@ def arm_and_takeoff(aTargetAltitude):
 print("Uploading %d waypoints to vehicle..." % len(messages))
 cmds.upload()
 
-print "Arm and Takeoff"
+print("Arm and Takeoff")
 arm_and_takeoff(30)
 
 
-print "Starting mission"
+print("Starting mission")
 
 # Reset mission set to first (0) waypoint
 vehicle.commands.next=0
@@ -207,20 +207,20 @@ def arm_and_takeoff(aTargetAltitude):
 time_start = time.time()
 while time.time() - time_start < 60:
     nextwaypoint=vehicle.commands.next
-    print 'Distance to waypoint (%s): %s' % (nextwaypoint, distance_to_current_waypoint())
+    print('Distance to waypoint (%s): %s' % (nextwaypoint, distance_to_current_waypoint()))
 
     if nextwaypoint==len(messages):
-        print "Exit 'standard' mission when start heading to final waypoint"
+        print("Exit 'standard' mission when start heading to final waypoint")
         break;
     time.sleep(1)
 
-print 'Return to launch'
+print('Return to launch')
 while (vehicle.mode.name != "RTL"):
     vehicle.mode = VehicleMode("RTL")
     time.sleep(0.1)
 
 #Close vehicle object before exiting script
-print "Close vehicle object"
+print("Close vehicle object")
 vehicle.close()
 
 # Shut down simulator if it was started.

examples/follow_me/follow_me.py

@@ -13,6 +13,7 @@
 
 Example documentation: http://python.dronekit.io/examples/follow_me.html
 """
+from __future__ import print_function
 
 from dronekit import connect, VehicleMode, LocationGlobalRelative
 import gps
@@ -38,7 +39,7 @@
     connection_string = sitl.connection_string()
 
 # Connect to the Vehicle
-print 'Connecting to vehicle on: %s' % connection_string
+print('Connecting to vehicle on: %s' % connection_string)
 vehicle = connect(connection_string, wait_ready=True)
 
 
@@ -48,31 +49,31 @@ def arm_and_takeoff(aTargetAltitude):
     Arms vehicle and fly to aTargetAltitude.
     """
 
-    print "Basic pre-arm checks"
+    print("Basic pre-arm checks")
     # Don't let the user try to arm until autopilot is ready
     while not vehicle.is_armable:
-        print " Waiting for vehicle to initialise..."
+        print(" Waiting for vehicle to initialise...")
         time.sleep(1)
 
 
-    print "Arming motors"
+    print("Arming motors")
     # Copter should arm in GUIDED mode
     vehicle.mode = VehicleMode("GUIDED")
     vehicle.armed = True    
 
     while not vehicle.armed:      
-        print " Waiting for arming..."
+        print(" Waiting for arming...")
         time.sleep(1)
 
-    print "Taking off!"
+    print("Taking off!")
     vehicle.simple_takeoff(aTargetAltitude) # Take off to target altitude
 
     # Wait until the vehicle reaches a safe height before processing the goto (otherwise the command 
     #  after Vehicle.simple_takeoff will execute immediately).
     while True:
-        print " Altitude: ", vehicle.location.global_relative_frame.alt      
+        print(" Altitude: ", vehicle.location.global_relative_frame.alt)      
         if vehicle.location.global_relative_frame.alt>=aTargetAltitude*0.95: #Trigger just below target alt.
-            print "Reached target altitude"
+            print("Reached target altitude")
             break
         time.sleep(1)
 
@@ -88,17 +89,17 @@ def arm_and_takeoff(aTargetAltitude):
     while True:
 
         if vehicle.mode.name != "GUIDED":
-            print "User has changed flight modes - aborting follow-me"
+            print("User has changed flight modes - aborting follow-me")
             break    
 
         # Read the GPS state from the laptop
-        gpsd.next()
+        next(gpsd)
 
         # Once we have a valid location (see gpsd documentation) we can start moving our vehicle around
         if (gpsd.valid & gps.LATLON_SET) != 0:
             altitude = 30  # in meters
             dest = LocationGlobalRelative(gpsd.fix.latitude, gpsd.fix.longitude, altitude)
-            print "Going to: %s" % dest
+            print("Going to: %s" % dest)
 
             # A better implementation would only send new waypoints if the position had changed significantly
             vehicle.simple_goto(dest)
@@ -108,11 +109,11 @@ def arm_and_takeoff(aTargetAltitude):
             time.sleep(2)
 
 except socket.error:
-    print "Error: gpsd service does not seem to be running, plug in USB GPS or run run-fake-gps.sh"
+    print("Error: gpsd service does not seem to be running, plug in USB GPS or run run-fake-gps.sh")
     sys.exit(1)
 
 #Close vehicle object before exiting script
-print "Close vehicle object"
+print("Close vehicle object")
 vehicle.close()
 
 # Shut down simulator if it was started.

examples/gcs/microgcs.py

@@ -4,6 +4,7 @@
 """
 © Copyright 2015-2016, 3D Robotics.
 """
+from __future__ import print_function
 #
 # This is a small example of the python drone API - an ultra minimal GCS
 #
@@ -32,7 +33,7 @@
     connection_string = sitl.connection_string()
 
 # Connect to the Vehicle
-print 'Connecting to vehicle on: %s' % connection_string
+print('Connecting to vehicle on: %s' % connection_string)
 vehicle = connect(connection_string, wait_ready=True)
 
 def setMode(mode):