Remove explicit metaclass definitions (PR #90)

This PR makes DeviceMeta a subclass of Boost.Python.class, so the metaclass definition is automatically propagated to the subclasses of Device.

It also fixes a fundamental issue with asyncio servers that I hadn't noticed until today, see 995db76.

The docs and examples have been simplified (1890f6c and 64c8cc9 promote the run_server method and remove the metaclass definitions).

It also fixes issue #74, see 38e1eec (unrelated, but it made my debugging easier).

doc/_static/PowerSupplyDS.py

@@ -7,23 +7,21 @@
 import numpy
 
 from tango import AttrQuality, AttrWriteType, DispLevel, DevState, DebugIt
-from tango.server import Device, DeviceMeta, attribute, command, pipe, run
-from tango.server import device_property
+from tango.server import Device, attribute, command, pipe, device_property
 
 
 class PowerSupply(Device):
-    __metaclass__ = DeviceMeta
 
     voltage = attribute(label="Voltage", dtype=float,
                         display_level=DispLevel.OPERATOR,
                         access=AttrWriteType.READ,
-                        unit="V",format="8.4f",
+                        unit="V", format="8.4f",
                         doc="the power supply voltage")
 
     current = attribute(label="Current", dtype=float,
                         display_level=DispLevel.EXPERT,
                         access=AttrWriteType.READ_WRITE,
-                        unit="A",format="8.4f",
+                        unit="A", format="8.4f",
                         min_value=0.0, max_value=8.5,
                         min_alarm=0.1, max_alarm=8.4,
                         min_warning=0.5, max_warning=8.0,
@@ -39,16 +37,16 @@ class PowerSupply(Device):
 
     host = device_property(dtype=str)
     port = device_property(dtype=int, default_value=9788)
-    
+
     def init_device(self):
         Device.init_device(self)
         self.__current = 0.0
         self.set_state(DevState.STANDBY)
-    
+
     def read_voltage(self):
         self.info_stream("read_voltage(%s, %d)", self.host, self.port)
         return 9.99, time.time(), AttrQuality.ATTR_WARNING
-    
+
     def get_current(self):
         return self.__current
 
@@ -76,12 +74,12 @@ def TurnOff(self):
         self.set_state(DevState.OFF)
 
     @command(dtype_in=float, doc_in="Ramp target current",
-             dtype_out=bool, doc_out="True if ramping went well, False otherwise")
+             dtype_out=bool, doc_out="True if ramping went well, "
+             "False otherwise")
     def Ramp(self, target_current):
         # should do the ramping
         return True
-
-
-if __name__ == "__main__":
-    run([PowerSupply])
 
+
+if __name__ == "__main__":
+    PowerSupply.run_server()

doc/_templates/index.html

@@ -87,7 +87,6 @@ <h1>Welcome to PyTango documentation!</h1>
 
 
 <span class="k">class</span> <span class="nc">Clock</span><span class="p">(</span><span class="n">Device</span><span class="p">):</span>
-    <span class="n">__metaclass__</span> <span class="o">=</span> <span class="n">DeviceMeta</span>
 
     <span class="n">time</span> <span class="o">=</span> <span class="n">attribute</span><span class="p">()</span>
 

doc/howto.rst

@@ -307,13 +307,10 @@ high level API
    :linenos:
 
     import time
-    from tango.server import run
-    from tango.server import Device, DeviceMeta
-    from tango.server import attribute, command, pipe
+    from tango.server import Device, attribute, command, pipe
 
 
     class Clock(Device):
-        __metaclass__ = DeviceMeta
 
         @attribute
         def time(self):
@@ -332,37 +329,32 @@ high level API
 
 
     if __name__ == "__main__":
-        run([Clock])
+        Clock.run_server()
 
 
-**line 2-4**
+**line 2**
     import the necessary symbols
 
-**line 7**
+**line 5**
     tango device class definition. A Tango device must inherit from
     :class:`tango.server.Device`
 
-**line 8**
-    mandatory *magic* line. A Tango device must define the metaclass as
-    :class:`tango.server.DeviceClass`. This has to be done due to a limitation
-    on boost-python
-
-**line 10-12**
+**line 7-9**
     definition of the *time* attribute. By default, attributes are double, scalar,
     read-only. Check the :class:`~tango.server.attribute` for the complete
     list of attribute options.
 
-**line 14-16**
+**line 11-13**
     the method *strftime* is exported as a Tango command. In receives a string
     as argument and it returns a string. If a method is to be exported as a
     Tango command, it must be decorated as such with the
     :func:`~tango.server.command` decorator
 
-**line 18-23**
+**line 15-20**
     definition of the *info* pipe. Check the :class:`~tango.server.pipe`
     for the complete list of pipe options.
 
-**line 28**
+**line 24**
     start the Tango run loop. The mandatory argument is a list of python classes
     that are to be exported as Tango classes. Check :func:`~tango.server.run`
     for the complete list of options
@@ -383,13 +375,12 @@ using the high level API. The example contains:
     from time import time
     from numpy.random import random_sample
 
-    from tango import AttrQuality, AttrWriteType, DispLevel, run
-    from tango.server import Device, DeviceMeta, attribute, command
+    from tango import AttrQuality, AttrWriteType, DispLevel
+    from tango.server import Device, attribute, command
     from tango.server import class_property, device_property
 
 
     class PowerSupply(Device):
-        __metaclass__ = DeviceMeta
 
         current = attribute(label="Current", dtype=float,
                             display_level=DispLevel.EXPERT,
@@ -428,17 +419,7 @@ using the high level API. The example contains:
 
 
     if __name__ == "__main__":
-        run([PowerSupply])
-
-
-.. note::
-    the ``__metaclass__`` statement is mandatory due to a limitation in the
-    *boost-python* library used by PyTango.
-
-    If you are using python 3 you can write instead::
-
-        class PowerSupply(Device, metaclass=DeviceMeta)
-            pass
+        PowerSupply.run_server()
 
 .. _logging:
 
@@ -573,29 +554,27 @@ separated python files: A :class:`PLC` class in a :file:`PLC.py`::
 
     # PLC.py
 
-    from tango.server import Device, DeviceMeta, run
+    from tango.server import Device
 
     class PLC(Device):
-        __metaclass__ = DeviceMeta
 
         # bla, bla my PLC code
 
     if __name__ == "__main__":
-        run([PLC])
+        PLC.run_server()
 
 ... and a :class:`IRMirror` in a :file:`IRMirror.py`::
 
     # IRMirror.py
 
-    from tango.server import Device, DeviceMeta, run
+    from tango.server import Device
 
     class IRMirror(Device):
-        __metaclass__ = DeviceMeta
 
         # bla, bla my IRMirror code
 
     if __name__ == "__main__":
-        run([IRMirror])
+        IRMirror.run_server()
 
 You want to create a Tango server called `PLCMirror` that is able to contain
 devices from both PLC and IRMirror classes. All you have to do is write
@@ -683,10 +662,9 @@ point attribute with the specified name::
 
 
     from tango import Util, Attr
-    from tango.server import DeviceMeta, Device, command
+    from tango.server import Device, command
 
     class MyDevice(Device):
-    	__metaclass__ = DeviceMeta
 
 	@command(dtype_in=str)
         def CreateFloatAttribute(self, attr_name):
@@ -730,10 +708,9 @@ creates a device of some arbitrary class (the example assumes the tango commands
 with two strings. No error processing was done on the code for simplicity sake)::
 
     from tango import Util
-    from tango.server import DeviceMeta, Device, command
+    from tango.server import Device, command
 
     class MyDevice(Device):
-    	__metaclass__ = DeviceMeta
 
 	@command(dtype_in=[str])
         def CreateDevice(self, pars):