diff options
| -rw-r--r-- | src/zope/interface/declarations.py | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/src/zope/interface/declarations.py b/src/zope/interface/declarations.py index f8337a1..83f424c 100644 --- a/src/zope/interface/declarations.py +++ b/src/zope/interface/declarations.py @@ -136,7 +136,13 @@ class _ImmutableDeclaration(Declaration): @__bases__.setter def __bases__(self, new_bases): - if new_bases: + # We expect the superclass constructor to set ``self.__bases__ = ()``. + # Rather than attempt to special case that in the constructor and allow + # setting __bases__ only at that time, it's easier to just allow setting + # the empty tuple at any time. That makes ``x.__bases__ = x.__bases__`` a nice + # no-op too. (Skipping the superclass constructor altogether is a recipe + # for maintenance headaches.) + if new_bases != (): raise TypeError("Cannot set non-empty bases on shared empty Declaration.") @property |