device: pass device constructor arguments as a dict (issue #91)

Pass arguments to construct the device as a dict instead of
assuming they are the leftovers kwargs of microscope.device().
This change prevents issues if a device argument name clashes
with the device server arguments (cls, host, port, and uid).

Also make the uid argument appear after the new conf argument
because most devices will need `conf` while uid is specific to
floating devices.

Author: carandraug

NEWS

@@ -4,6 +4,12 @@ python-microscope releases.
 Version 0.3.0 (yyyy/mm/dd)
 --------------------------
 
+* Backwards incompatible changes:
+
+  * `microscope.device()`, function used create a device definition,
+    changed signature.  The arguments to the device constructor must
+    now be passed as a dict.
+
 * Python 3.5 or later is now required.  Python 2 is no longer
   supported.  This drops the dependency on the six and enum34.
 

doc/examples.rst

@@ -61,8 +61,8 @@ Configurations
   from microscope.testsuite.devices import TestFilterWheel
 
   DEVICES = [
-      device(TestCamera, '127.0.0.1', 8005, otherargs=1,),
+      device(TestCamera, '127.0.0.1', 8005, {'otherargs' : 1}),
       device(TestLaser, '127.0.0.1', 8006),
       device(TestFilterWheel, '127.0.0.1', 8007,
-             filters=[(0, 'GFP', 525), (1, 'RFP'), (2, 'Cy5')]),
+             {'filters' : [(0, 'GFP', 525), (1, 'RFP'), (2, 'Cy5')]}),
   ]

microscope/devices.py

@@ -156,16 +156,21 @@ def values(self):
                 return values
 
 
-def device(cls, host, port, uid=None, **kwargs):
+def device(cls, host, port, conf={}, uid=None):
     """Define a device and where to serve it.
 
-    A device definition for use in config files.
+    A device definition for use in deviceserver config files.
 
-    Defines a device of type cls, served on host:port.
-    UID is used to identify 'floating' devices (see below).
-    kwargs can be used to pass any other parameters to cls.__init__.
+    Args:
+        cls (type): type/class of device to serve.
+        host (str): hostname or ip address serving the device.
+        port (int): port number used to serve the device.
+        conf (dict): keyword arguments to construct the device.  The
+            device is effectively constructed with `cls(**conf)`.
+        uid (str): used to identify "floating" devices (see
+            documentation for :class:`FloatingDeviceMixin`)
     """
-    return dict(cls=cls, host=host, port=int(port), uid=uid, **kwargs)
+    return dict(cls=cls, host=host, port=int(port), uid=uid, conf=conf)
 
 
 class FloatingDeviceMixin(object):

microscope/deviceserver.py

@@ -137,13 +137,7 @@ def run(self):
         logger.addFilter(Filter())
         logger.debug("Debugging messages on.")
 
-        ## The device definition includes stuff that were never
-        ## meant for the device.  Remove those.
-        init_kwargs = self._device_def.copy()
-        for def_key in ['cls', 'host', 'port', 'uid']:
-            init_kwargs.pop(def_key)
-
-        self._device = self._device_def['cls'](**init_kwargs)
+        self._device = self._device_def['cls'](**self._device_def['conf'])
         while not self.exit_event.is_set():
             try:
                 self._device.initialize()
@@ -258,7 +252,7 @@ def term_func(sig, frame):
             uid_to_port = None
 
         for dev in devs:
-            dev['index'] = count
+            dev['conf']['index'] = count
             servers.append(DeviceServer(dev, uid_to_host, uid_to_port,
                                         exit_event=exit_event))
             servers[-1].start()

microscope/testsuite/deviceserver_test.py

@@ -24,6 +24,8 @@
 import unittest
 import unittest.mock
 
+import microscope.clients
+import microscope.devices
 import microscope.deviceserver
 
 from microscope.devices import device
@@ -78,9 +80,9 @@ def tearDown(self):
 
 class TestStarting(BaseTestServeDevices):
     DEVICES = [
-        device(TestCamera, '127.0.0.1', 8001, otherargs=1,),
+        device(TestCamera, '127.0.0.1', 8001, {'otherargs' : 1}),
         device(TestFilterWheel, '127.0.0.1', 8003,
-               filters=[(0, 'GFP', 525), (1, 'RFP'), (2, 'Cy5')]),
+               {'filters' : [(0, 'GFP', 525), (1, 'RFP'), (2, 'Cy5')]}),
     ]
 
     def test_standard(self):
@@ -101,5 +103,32 @@ def test_empty_devices(self):
                         "not dying for empty list of devices")
 
 
+class DeviceWithPort(microscope.devices.Device):
+    def __init__(self, port, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._port = port
+
+    @property
+    def port(self):
+        return self._port
+
+    def _on_shutdown(self):
+        pass
+
+    def initialize(self):
+        pass
+
+
+class TestClashingArguments(BaseTestServeDevices):
+    """Device server and device constructor arguments do not clash"""
+    DEVICES = [
+        device(DeviceWithPort, '127.0.0.1', 8000, {'port' : 7000}),
+    ]
+    def test_port_conflict(self):
+        time.sleep(2)
+        client = microscope.clients.Client('PYRO:DeviceWithPort@127.0.0.1:8000')
+        self.assertEqual(client.port, 7000)
+
+
 if __name__ == '__main__':
     unittest.main()