new syntax for parameter/commands/properties

New Syntax:

- define properties and parameters as class attributes directly
  instead of items in class attribute dicts
- define commands with decorator @usercommand(...)
- old syntax is still supported for now

still to do (with decreasing priority):
- turn parameters into descriptors (vs. creating getters/setters)
- migrate all existing code to new syntax
- get rid of or reduce code in metaclasses using __set_name__ and
  __init_subclass__ instead, including a fix for allowing py < 3.6

Change-Id: Id47e0f89c506f50c40fa518b01822c6e5bbf4e98
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/24991
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/modules.py

@@ -208,6 +208,7 @@ class Module(HasProperties, metaclass=ModuleMeta):
             if pname in cfgdict:
                 if not pobj.readonly and pobj.initwrite is not False:
                     # parameters given in cfgdict have to call write_<pname>
+                    # TODO: not sure about readonly (why not a parameter which can only be written from config?)
                     try:
                         pobj.value = pobj.datatype(cfgdict[pname])
                     except BadValueError as e:
@@ -216,7 +217,7 @@ class Module(HasProperties, metaclass=ModuleMeta):
             else:
                 if pobj.default is None:
                     if pobj.needscfg:
-                        raise ConfigError('Module %s: Parameter %r has no default '
+                        raise ConfigError('Parameter %s.%s has no default '
                                           'value and was not given in config!' %
                                           (self.name, pname))
                     # we do not want to call the setter for this parameter for now,
@@ -231,9 +232,10 @@ class Module(HasProperties, metaclass=ModuleMeta):
                     except BadValueError as e:
                         raise ProgrammingError('bad default for %s.%s: %s'
                                                % (name, pname, e))
-                    if pobj.initwrite:
+                    if pobj.initwrite and not pobj.readonly:
                         # we will need to call write_<pname>
                         # if this is not desired, the default must not be given
+                        # TODO: not sure about readonly (why not a parameter which can only be written from config?)
                         pobj.value = value
                         self.writeDict[pname] = value
                     else:
@@ -542,6 +544,14 @@ class Communicator(Module):
                            ),
     }
 
+    def do_communicate(self, command):
+        """communicate command
+
+        :param command: the command to be sent
+        :return: the reply
+        """
+        raise NotImplementedError()
+
 
 class Attached(Property):
     # we can not put this to properties.py, as it needs datatypes