lib.enum: privatize internal attributes in EnumView/FlagView

amaranth/lib/enum.py

@@ -234,16 +234,16 @@ def __init__(self, enum, target):
                             .format(target)) from e
         if cast_target.shape() != enum.as_shape():
             raise TypeError("EnumView target must have the same shape as the enum")
-        self.enum = enum
-        self.target = cast_target
+        self.__enum = enum
+        self.__target = cast_target
 
     def shape(self):
         """Returns the underlying enum type."""
-        return self.enum
+        return self.__enum
 
     def as_value(self):
         """Returns the underlying value."""
-        return self.target
+        return self.__target
 
     def eq(self, other):
         """Assign to the underlying value.
@@ -296,21 +296,25 @@ def __eq__(self, other):
         :class:`Value`
             The result of the equality comparison, as a single-bit value.
         """
-        if isinstance(other, self.enum):
-            other = self.enum(Value.cast(other))
-        if not isinstance(other, EnumView) or other.enum is not self.enum:
-            raise TypeError("an EnumView can only be compared to value or other EnumView of the same enum type")
-        return self.target == other.target
+        enum_cls = self.shape()
+        if isinstance(other, enum_cls):
+            other = enum_cls(Value.cast(other))
+        if not isinstance(other, EnumView) or other.shape() is not enum_cls:
+            raise TypeError("an EnumView can only be compared to value or other EnumView of "
+                            "the same enum type")
+        return self.as_value() == other.as_value()
 
     def __ne__(self, other):
-        if isinstance(other, self.enum):
-            other = self.enum(Value.cast(other))
-        if not isinstance(other, EnumView) or other.enum is not self.enum:
-            raise TypeError("an EnumView can only be compared to value or other EnumView of the same enum type")
-        return self.target != other.target
+        enum_cls = self.shape()
+        if isinstance(other, enum_cls):
+            other = enum_cls(Value.cast(other))
+        if not isinstance(other, EnumView) or other.shape() is not enum_cls:
+            raise TypeError("an EnumView can only be compared to value or other EnumView of "
+                            "the same enum type")
+        return self.as_value() != other.as_value()
 
     def __repr__(self):
-        return f"{type(self).__qualname__}({self.enum.__qualname__}, {self.target!r})"
+        return f"{type(self).__qualname__}({self.__enum.__qualname__}, {self.__target!r})"
 
 
 class FlagView(EnumView):
@@ -330,21 +334,23 @@ def __invert__(self):
         -------
         :class:`FlagView`
         """
-        if hasattr(self.enum, "_boundary_") and self.enum._boundary_ in (EJECT, KEEP):
-            return self.enum._amaranth_view_class_(self.enum, ~self.target)
+        enum_cls = self.shape()
+        if hasattr(enum_cls, "_boundary_") and enum_cls._boundary_ in (EJECT, KEEP):
+            return enum_cls._amaranth_view_class_(enum_cls, ~self.as_value())
         else:
             singles_mask = 0
-            for flag in self.enum:
+            for flag in enum_cls:
                 if (flag.value & (flag.value - 1)) == 0:
                     singles_mask |= flag.value
-            return self.enum._amaranth_view_class_(self.enum, ~self.target & singles_mask)
+            return enum_cls._amaranth_view_class_(enum_cls, ~self.as_value() & singles_mask)
 
     def __bitop(self, other, op):
-        if isinstance(other, self.enum):
-            other = self.enum(Value.cast(other))
-        if not isinstance(other, FlagView) or other.enum is not self.enum:
+        enum_cls = self.shape()
+        if isinstance(other, enum_cls):
+            other = enum_cls(Value.cast(other))
+        if not isinstance(other, FlagView) or other.shape() is not enum_cls:
             raise TypeError("a FlagView can only perform bitwise operation with a value or other FlagView of the same enum type")
-        return self.enum._amaranth_view_class_(self.enum, op(self.target, other.target))
+        return enum_cls._amaranth_view_class_(enum_cls, op(self.as_value(), other.as_value()))
 
     def __and__(self, other):
         """Performs a bitwise AND and returns another :class:`FlagView`.