hardbyte · felixdivo · Jun 4, 2018 · Jun 4, 2018 · Jun 4, 2018 · Jun 4, 2018
diff --git a/can/bus.py b/can/bus.py
@@ -28,7 +28,7 @@ class BusABC(object):
     channel_info = 'unknown'
 
     @abstractmethod
-    def __init__(self, channel=None, can_filters=None, **config):
+    def __init__(self, channel, can_filters=None, **config):
         """Construct and open a CAN bus instance of the specified type.
 
         Subclasses should call though this method with all given parameters

diff --git a/can/interface.py b/can/interface.py
@@ -12,6 +12,7 @@
 import sys
 import importlib
 import logging
+import re
 
 import can
 from .bus import BusABC
@@ -72,14 +73,21 @@ def _get_class_for_interface(interface):
 
 class Bus(BusABC):
     """
-    Instantiates a CAN Bus of the given `bustype`, falls back to reading a
+    Instantiates a CAN Bus of the given ``interface``, falls back to reading a
     configuration file from default locations.
     """
 
     @staticmethod
-    def __new__(cls, *args, **config):
+    def __new__(cls, channel=None, *args, **config):
         """
-        Takes the same arguments as :class:`can.BusABC.__init__` with the addition of:
+        Takes the same arguments as :class:`can.BusABC.__init__`.
+        Some might have a special meaning, see below.
+
+        :param channel:
+            Set to ``None`` to let it be reloved automatically from the default
+            configuration. That might fail, see below.
+
+            Expected type is backend dependent.
 
         :param dict config:
             Should contain an ``interface`` key with a valid interface name. If not,
@@ -93,6 +101,8 @@ def __new__(cls, *args, **config):
         """
 
         # figure out the rest of the configuration; this might raise an error
+        if channel is not None:
+            config['channel'] = channel
         config = load_config(config=config)
 
         # resolve the bus class to use for that interface
@@ -101,12 +111,14 @@ def __new__(cls, *args, **config):
         # remove the 'interface' key so it doesn't get passed to the backend
         del config['interface']
 
-        # make sure the bus can handle this config
+        # make sure the bus can handle this config format
         if 'channel' not in config:
-            raise ValueError("channel argument missing")
+            raise ValueError("'channel' argument missing")
+        else:
+            channel = config['channel']
+            del config['channel']
 
-        # the channel attribute should be present in **config
-        return cls(*args, **config)
+        return cls(channel, *args, **config)
 
 
 def detect_available_configs(interfaces=None):

diff --git a/can/interfaces/ics_neovi/neovi_bus.py b/can/interfaces/ics_neovi/neovi_bus.py
@@ -82,7 +82,7 @@ class NeoViBus(BusABC):
     https://github.com/intrepidcs/python_ics
     """
 
-    def __init__(self, channel=None, can_filters=None, **config):
+    def __init__(self, channel, can_filters=None, **config):
         """
         :param int channel:
             The Channel id to create this bus with.

diff --git a/can/interfaces/nican.py b/can/interfaces/nican.py
@@ -130,8 +130,7 @@ class NicanBus(BusABC):
 
     """
 
-    def __init__(self, channel, can_filters=None, bitrate=None, log_errors=True,
-                 **kwargs):
+    def __init__(self, channel, can_filters=None, bitrate=None, log_errors=True, **kwargs):
         """
         :param str channel:
             Name of the object to open (e.g. 'CAN0')

diff --git a/can/interfaces/socketcan/socketcan_ctypes.py b/can/interfaces/socketcan/socketcan_ctypes.py
@@ -45,10 +45,7 @@ class SocketcanCtypes_Bus(BusABC):
     Implements :meth:`can.BusABC._detect_available_configs`.
     """
 
-    def __init__(self,
-                 channel='vcan0',
-                 receive_own_messages=False,
-                 *args, **kwargs):
+    def __init__(self, channel, receive_own_messages=False, *args, **kwargs):
         """
         :param str channel:
             The can interface name with which to create this bus. An example channel

diff --git a/test/back2back_test.py b/test/back2back_test.py
@@ -23,9 +23,9 @@
 TIMEOUT = 0.1
 
 INTERFACE_1 = 'virtual'
-CHANNEL_1 = 'vcan0'
+CHANNEL_1 = 'virtual_channel_0'
 INTERFACE_2 = 'virtual'
-CHANNEL_2 = 'vcan0'
+CHANNEL_2 = 'virtual_channel_0'
 
 
 class Back2BackTestCase(unittest.TestCase):
@@ -35,16 +35,16 @@ class Back2BackTestCase(unittest.TestCase):
     """
 
     def setUp(self):
-        self.bus1 = can.interface.Bus(channel=CHANNEL_1,
-                                      bustype=INTERFACE_1,
-                                      bitrate=BITRATE,
-                                      fd=TEST_CAN_FD,
-                                      single_handle=True)
-        self.bus2 = can.interface.Bus(channel=CHANNEL_2,
-                                      bustype=INTERFACE_2,
-                                      bitrate=BITRATE,
-                                      fd=TEST_CAN_FD,
-                                      single_handle=True)
+        self.bus1 = can.Bus(channel=CHANNEL_1,
+                            bustype=INTERFACE_1,
+                            bitrate=BITRATE,
+                            fd=TEST_CAN_FD,
+                            single_handle=True)
+        self.bus2 = can.Bus(channel=CHANNEL_2,
+                            bustype=INTERFACE_2,
+                            bitrate=BITRATE,
+                            fd=TEST_CAN_FD,
+                            single_handle=True)
 
     def tearDown(self):
         self.bus1.shutdown()
@@ -146,14 +146,14 @@ def setUp(self):
         print("testing python-can's socketcan version:",
               socketcan_version)
 
-        self.bus1 = can.interface.Bus(channel="vcan0",
-                                      bustype=socketcan_version,
-                                      bitrate=250000,
-                                      fd=TEST_CAN_FD)
-        self.bus2 = can.interface.Bus(channel="vcan0",
-                                      bustype=socketcan_version,
-                                      bitrate=250000,
-                                      fd=TEST_CAN_FD)
+        self.bus1 = can.Bus(channel="vcan0",
+                            bustype=socketcan_version,
+                            bitrate=250000,
+                            fd=TEST_CAN_FD)
+        self.bus2 = can.Bus(channel="vcan0",
+                            bustype=socketcan_version,
+                            bitrate=250000,
+                            fd=TEST_CAN_FD)
 
     def tearDown(self):
         self.bus1.shutdown()

diff --git a/test/listener_test.py b/test/listener_test.py
@@ -4,7 +4,7 @@
 """
 """
 
-from __future__ import absolute_import
+from __future__ import absolute_import, print_function
 
 from time import sleep
 import unittest
@@ -18,12 +18,12 @@
 
 from .data.example_data import generate_message
 
-channel = 'vcan0'
+channel = 'virtual_channel_0'
 can.rc['interface'] = 'virtual'
 
 logging.getLogger('').setLevel(logging.DEBUG)
 
-# make tests more reproducible
+# makes the random number generator deterministic
 random.seed(13339115)
 
 
@@ -54,7 +54,7 @@ def testClassesImportable(self):
 
         self.assertTrue(hasattr(can, 'LogReader'))
 
-        self.assertTrue(hasattr(can.io.player, 'MessageSync'))
+        self.assertTrue(hasattr(can, 'MessageSync'))
 
 
 class BusTest(unittest.TestCase):
@@ -106,7 +106,7 @@ def test_filetype_to_instance(extension, klass):
         # test file extensions that are not supported
         with self.assertRaisesRegexp(NotImplementedError, "xyz_42"):
             test_filetype_to_instance("xyz_42", can.Printer)
-        with self.assertRaises(BaseException):
+        with self.assertRaises(Exception):
             test_filetype_to_instance(None, can.Printer)
 
     def testLoggerTypeResolution(self):