Bunch of Tiny Fixes and Enhancements (#41)

* Use setuptools to allow the extras_require to work in python3.6

This also declares some hidden dependencies for the underlying
connection protocols, but note that they are normally reliant
on system-packaged versions, which is a bit less than optimal.

* In message, on assert of incoming type, note failing type

* In utilities, guard against truncated input.

* In demo allow for specifying different connections and demos on command line

Also addresses a crash in led demo where parameters x and y were not provided
to an empty lamba that was passed in.

* Remove commentted line, apply black formatting

* Raise TypeError when an incorrectly-typed message is received

* Apply black automatic formatting to the utilities module

examples/demo.py

@@ -13,7 +13,10 @@ log = logging.getLogger("demo")
 def demo_led_colors(movehub):
     # LED colors demo
     log.info("LED colors demo")
-    movehub.led.subscribe(lambda x, y: None)
+    # We get a response with payload and port, not x and y here...
+    def colour_callback(**named):
+        log.info("LED Color callback: %s", named)
+    movehub.led.subscribe(colour_callback)
     for color in list(COLORS.keys())[1:] + [COLOR_BLACK]:
         log.info("Setting LED color to: %s", COLORS[color])
         movehub.led.set_color(color)
@@ -180,10 +183,78 @@ def demo_all(movehub):
     demo_color_sensor(movehub)
     demo_motor_sensors(movehub)
 
+DEMO_CHOICES = {
+    'all':demo_all,
+    'voltage':demo_voltage,
+    'led_colors':demo_led_colors,
+    'motors_timed':demo_motors_timed,
+    'motors_angled':demo_motors_angled,
+    'port_cd_motor':demo_port_cd_motor,
+    'tilt_sensor':demo_tilt_sensor_simple,
+    'tilt_sensor_precise':demo_tilt_sensor_precise,
+    'color_sensor':demo_color_sensor,
+    'motor_sensors':demo_motor_sensors,
+}
+
+def get_options():
+    import argparse 
+    parser = argparse.ArgumentParser(
+        description='Demonstrate move-hub communications',
+    )
+    parser.add_argument(
+        '-c','--connection',
+        default='auto://',
+        help='''Specify connection URL to use, `protocol://mac?param=X` with protocol in:
+    "gatt","pygatt","gattlib","gattool", "bluepy","bluegiga"'''
+    )
+    parser.add_argument(
+        '-d','--demo',
+        default='all',
+        choices = sorted(DEMO_CHOICES.keys()),
+        help="Run a particular demo, default all"
+    )
+    return parser
+
+def connection_from_url(url):
+    import pylgbst
+    if url == 'auto://':
+        return None 
+    try:
+        from urllib.parse import urlparse, parse_qs
+    except ImportError:
+        from urlparse import urlparse, parse_qs
+    parsed = urlparse(url)
+    name = 'get_connection_%s'%(parsed.scheme)
+    factory = getattr( pylgbst, name, None)
+    if not factory:
+        raise ValueError("Unrecognised URL scheme/protocol, expect a get_connection_<protocol> in pylgbst: %s"%(parsed.protocol))
+    params = {}
+    if parsed.netloc.strip():
+        params['hub_mac'] = parsed.netloc
+    for key,value in parse_qs(parsed.query).items():
+        if len(value) == 1:
+            params[key] = value[0]
+        else:
+            params[key] = value
+    return factory(
+        **params
+    )
 
 if __name__ == '__main__':
     logging.basicConfig(level=logging.INFO)
+    parser = get_options()
+    options = parser.parse_args()
+    parameters = {}
+    try:
+        connection = connection_from_url(options.connection)
+        parameters['connection'] = connection
+    except ValueError as err:
+        parser.error(error.args[0])
+        connection 
 
-    hub = MoveHub()
-    demo_all(hub)
+    hub = MoveHub(**parameters)
+    try:
+        demo = DEMO_CHOICES[options.demo]
+        demo(hub)
+    finally:
         hub.disconnect()

pylgbst/messages.py

@@ -173,7 +173,8 @@ class MsgHubAction(DownstreamMsg, UpstreamMsg):
         return super(MsgHubAction, self).bytes()
 
     def is_reply(self, msg):
-        assert isinstance(msg, MsgHubAction)
+        if not isinstance(msg, MsgHubAction):
+            raise TypeError("Unexpected message type: %s"%(msg.__class__,))
         if self.action == self.DISCONNECT and msg.action == self.UPSTREAM_DISCONNECT:
             return True
 

pylgbst/utilities.py

@@ -7,6 +7,8 @@ import logging
 import sys
 from struct import unpack
 
+log = logging.getLogger(__name__)
+
 if sys.version_info[0] == 2:
     import Queue as queue
 else:
@@ -15,22 +17,34 @@ else:
 queue = queue  # just to use it
 
 
+def check_unpack(seq, index, pattern, size):
+    """Check that we got size bytes, if so, unpack using pattern"""
+    data = seq[index : index + size]
+    if len(data) == size:
+        return unpack(pattern, data)[0]
+    else:
+        log.warning(
+            "Unpacking of %s bytes failed, insufficient data: %r", size, seq[index:]
+        )
+        raise ValueError(data, "Expected %s bytes" % (size,))
+
+
 def usbyte(seq, index):
-    return unpack("<B", seq[index:index + 1])[0]
+    return check_unpack(seq, index, "<B", 1)
 
 
 def ushort(seq, index):
-    return unpack("<H", seq[index:index + 2])[0]
+    return check_unpack(seq, index, "<H", 2)
 
 
 def usint(seq, index):
-    return unpack("<I", seq[index:index + 4])[0]
+    return check_unpack(seq, index, "<I", 4)
 
 
 def str2hex(data):  # we need it for python 2+3 compatibility
     # if sys.version_info[0] == 3:
     # data = bytes(data, 'ascii')
     if not isinstance(data, (bytes, bytearray)):
-        data = bytes(data, 'ascii')
+        data = bytes(data, "ascii")
     hexed = binascii.hexlify(data)
     return hexed

setup.py

@@ -1,16 +1,18 @@
-from distutils.core import setup
+from setuptools import setup
 
-setup(name='pylgbst',
-      description='Python library to interact with LEGO Move Hub (from Lego BOOST set)',
-      version='1.1.1',
-      author='Andrey Pokhilko',
-      author_email='apc4@ya.ru',
-      packages=['pylgbst', "pylgbst.comms"],
+setup(
+    name="pylgbst",
+    description="Python library to interact with LEGO Move Hub (from Lego BOOST set)",
+    version="1.1.1",
+    author="Andrey Pokhilko",
+    author_email="apc4@ya.ru",
+    packages=["pylgbst", "pylgbst.comms"],
     requires=[],
     extras_require={
-          'gatt': ["gatt"],
-          'gattlib': ["gattlib"],
-          'pygatt': ["pygatt"],
-          'bluepy': ["bluepy"],
-      }
+        # Note that dbus and gi are normally system packages
+        "gatt": ["gatt", "dbus", "gi"],
+        "gattlib": ["gattlib"],
+        "pygatt": ["pygatt", "pexpect"],
+        "bluepy": ["bluepy"],
+    },
 )