improve Attached

- allow a default value
- make copy method work properly

secop/modules.py

@@ -35,7 +35,7 @@ from secop.errors import BadValueError, CommunicationFailedError, ConfigError, \
 from secop.lib import formatException, mkthread, UniqueObject, generalConfig
 from secop.lib.enum import Enum
 from secop.params import Accessible, Command, Parameter
-from secop.properties import HasProperties, Property
+from secop.properties import HasProperties, Property, UNSET
 from secop.logging import RemoteLogHandler, HasComlog
 
 generalConfig.set_default('disable_value_range_check', False)  # check for problematic value range by default
@@ -879,9 +879,10 @@ class Attached(Property):
     assign a module name to this property in the cfg file,
     and the server will create an attribute with this module
     """
-    def __init__(self, basecls=Module, description='attached module', mandatory=True):
+    def __init__(self, basecls=Module, description='attached module', mandatory=True,
+                 default=UNSET):
         self.basecls = basecls
-        super().__init__(description, StringType(), mandatory=mandatory)
+        super().__init__(description, StringType(), mandatory=mandatory, value=default)
 
     def __get__(self, obj, owner):
         if obj is None:
@@ -891,3 +892,6 @@ class Attached(Property):
             return super().__get__(obj, owner)
         # return the module (called after startup)
         return obj.attachedModules.get(self.name)  # return None if not given
+
+    def copy(self):
+        return Attached(self.basecls, self.description, self.mandatory, self.value)