simplify status type declaration

- StatusType: simpler inheritance (inherit from module instead of Enum)
- StatusType: more robust for standard codes, give names only
- <Module>.Status is automatically extended
- Enum: accept duplicates with same name and value

Change-Id: Iad1dacf14c31fe6f4ae48e7560b29e49838e4f23
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/30716
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

frappy/datatypes.py

@@ -1242,7 +1242,12 @@ class LimitsType(TupleOf):
 
 
 class StatusType(TupleOf):
-    # shorten initialisation and allow access to status enumMembers from status values
+    """convenience type for status
+
+    :param first: an Enum or Module to inherit from, or the first member name
+    :param args: member names (codes will be taken from class attributes below)
+    :param kwds: additional members not matching the standard
+    """
     DISABLED = 0
     IDLE = 100
     STANDBY = 130
@@ -1250,7 +1255,7 @@ class StatusType(TupleOf):
     WARN = 200
     WARN_STANDBY = 230
     WARN_PREPARED = 250
-    UNSTABLE = 270  # no SECoP standard (yet)
+    UNSTABLE = 270  # not in SECoP standard (yet)
     BUSY = 300
     DISABLING = 310
     INITIALIZING = 320
@@ -1262,13 +1267,30 @@ class StatusType(TupleOf):
     ERROR = 400
     ERROR_STANDBY = 430
     ERROR_PREPARED = 450
+    UNKNOWN = 401  # not in SECoP standard (yet)
 
-    def __init__(self, enum):
-        super().__init__(EnumType(enum), StringType())
-        self._enum = enum
+    def __init__(self, first, *args, **kwds):
+        if first:
+            if isinstance(first, str):
+                args = (first,) + args
+                first = 'Status'  # enum name
+            else:
+                if not isinstance(first, Enum):
+                    # assume first is a Module with a status parameter
+                    try:
+                        first = first.status.datatype.members[0]._enum
+                    except AttributeError:
+                        raise ProgrammingError('first argument must be either str, Enum or a module') from None
+        else:
+            first = 'Status'  # enum name
+        bad = {n for n in args if n not in StatusType.__dict__ or n.startswith('_')}  # avoid built-in attributes
+        if bad:
+            raise ProgrammingError('positional arguments %r must be standard status code names' % bad)
+        self.enum = Enum(Enum(first, **{n: StatusType.__dict__[n] for n in args}), **kwds)
+        super().__init__(EnumType(self.enum), StringType())
 
     def __getattr__(self, key):
-        return getattr(self._enum, key)
+        return self.enum[key]
 
 
 def floatargs(kwds):