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):
+    def __init__(self, first, *args, **kwds):
-        super().__init__(EnumType(enum), StringType())
+        if first:
-        self._enum = enum
+            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):

frappy/lib/enum.py

@@ -264,8 +264,7 @@ class Enum(dict):
         names = set()
         values = set()
 
-        # pylint: disable=dangerous-default-value
+        def add(self, k, v):
-        def add(self, k, v, names=names, value=values):
             """helper for creating the enum members"""
             if v is None:
                 # sugar: take the next free number if value was None
@@ -285,10 +284,10 @@ class Enum(dict):
             v = _v
 
             # check for duplicates
-            if k in names:
+            if self.get(k, v) != v:
-                raise TypeError('duplicate name %r' % k)
+                raise TypeError('%s=%d conflicts with %s=%d' % (k, v, k, self[k]))
-            if v in values:
+            if self.get(v, k) != k:
-                raise TypeError('duplicate value %d (key=%r)' % (v, k))
+                raise TypeError('%s=%d conflicts with %s=%d' % (k, v, self[v].name, v))
 
             # remember it
             self[v] = self[k] = EnumMember(self, k, v)

frappy/modules.py

@@ -220,6 +220,11 @@ class HasAccessibles(HasProperties):
                 raise ProgrammingError('%s.%s defined, but %r is no parameter'
                                        % (cls.__name__, attrname, pname))
 
+        try:
+            # update Status type
+            cls.Status = cls.status.datatype.members[0]._enum
+        except AttributeError:
+            pass
         res = {}
         # collect info about properties
         for pn, pv in cls.propertyDict.items():
@@ -826,7 +831,6 @@ class Module(HasAccessibles):
 
 class Readable(Module):
     """basic readable module"""
-    # pylint: disable=invalid-name
     Status = Enum('Status',
                   IDLE=StatusType.IDLE,
                   WARN=StatusType.WARN,
@@ -834,11 +838,10 @@ class Readable(Module):
                   ERROR=StatusType.ERROR,
                   DISABLED=StatusType.DISABLED,
                   UNKNOWN=401,  # not SECoP standard. TODO: remove and adapt entangle and epics
-                  )  #: status codes
+                  )  #: status code Enum: extended automatically in inherited modules
-
     value = Parameter('current value of the module', FloatRange())
     status = Parameter('current status of the module', StatusType(Status),
-                       default=(Status.IDLE, ''))
+                       default=(StatusType.IDLE, ''))
     pollinterval = Parameter('default poll interval', FloatRange(0.1, 120),
                              default=5, readonly=False, export=True)
 
@@ -869,9 +872,7 @@ class Writable(Readable):
 class Drivable(Writable):
     """basic drivable module"""
 
-    Status = Enum(Readable.Status, BUSY=StatusType.BUSY)  #: status codes
+    status = Parameter(datatype=StatusType(Readable, 'BUSY'))  # extend Readable.status
-
-    status = Parameter(datatype=StatusType(Status))  # override Readable.status
 
     def isBusy(self, status=None):
         """check for busy, treating substates correctly

test/test_datatypes.py

@@ -26,7 +26,7 @@
 import pytest
 
 from frappy.datatypes import ArrayOf, BLOBType, BoolType, \
-    CommandType, ConfigError, DataType, Enum, EnumType, FloatRange, \
+    CommandType, ConfigError, DataType, EnumType, FloatRange, \
     IntRange, ProgrammingError, ScaledInteger, StatusType, \
     StringType, StructOf, TextType, TupleOf, get_datatype, \
     DiscouragedConversion
@@ -495,11 +495,23 @@ def test_Command():
 
 
 def test_StatusType():
-    status_codes = Enum('Status', IDLE=100, WARN=200, BUSY=300, ERROR=400)
+    dt = StatusType('IDLE', 'WARN', 'ERROR', 'DISABLED')
-    dt = StatusType(status_codes)
+    assert dt.IDLE == StatusType.IDLE == 100
-    assert dt.IDLE == status_codes.IDLE
+    assert dt.ERROR == StatusType.ERROR == 400
-    assert dt.ERROR == status_codes.ERROR
+
-    assert dt._enum == status_codes
+    dt2 = StatusType(None, IDLE=100, WARN=200, ERROR=400, DISABLED=0)
+    assert dt2.export_datatype() == dt.export_datatype()
+
+    dt3 = StatusType(dt.enum)
+    assert dt3.export_datatype() == dt.export_datatype()
+
+    with pytest.raises(ProgrammingError):
+        StatusType('__init__')  # built in attribute of StatusType
+
+    with pytest.raises(ProgrammingError):
+        StatusType(dt.enum, 'custom')  # not a standard attribute
+
+    StatusType(dt.enum, custom=499)  # o.k., if value is given
 
 
 def test_get_datatype():

test/test_lib_enum.py

@@ -83,3 +83,12 @@ def test_Enum_bool():
     e = Enum('OffOn', off=0, on=1)
     assert bool(e(0)) is False
     assert bool(e(1)) is True
+
+
+def test_Enum_duplicate():
+    e = Enum('x', a=1, b=2)
+    Enum(e, b=2, c=3)  # matching duplicate
+    with pytest.raises(TypeError):
+        Enum(e, b=3, c=4)  # duplicate name with value mismatch
+    with pytest.raises(TypeError):
+        Enum(e, c=1)  # duplicate value with name mismatch