Move __init__ from BaseSet into Set and ImmutableSet. This causes a
tiny amount of code duplication, but makes it possible to give BaseSet
an __init__ that raises an exception.
diff --git a/Lib/sets.py b/Lib/sets.py
index 4df30f8..c301c41 100644
--- a/Lib/sets.py
+++ b/Lib/sets.py
@@ -63,20 +63,12 @@
# Constructor
- def __init__(self, seq=None):
- """Construct a set, optionally initializing it from a sequence."""
- self._data = {}
- if seq is not None:
- # I don't know a faster way to do this in pure Python.
- # Custom code written in C only did it 65% faster,
- # preallocating the dict to len(seq); without
- # preallocation it was only 25% faster. So the speed of
- # this Python code is respectable. Just copying True into
- # a local variable is responsible for a 7-8% speedup.
- data = self._data
- value = True
- for key in seq:
- data[key] = value
+ def __init__(self):
+ """This is an abstract class."""
+ # Don't call this from a concrete subclass!
+ if self.__class__ is BaseSet:
+ raise NotImplementedError, ("BaseSet is an abstract class. "
+ "Use Set or ImmutableSet.")
# Standard protocols: __len__, __repr__, __str__, __iter__
@@ -289,9 +281,19 @@
def __init__(self, seq):
"""Construct an immutable set from a sequence."""
- # Override the constructor to make 'seq' a required argument
- BaseSet.__init__(self, seq)
self._hashcode = None
+ self._data = data = {}
+ # I don't know a faster way to do this in pure Python.
+ # Custom code written in C only did it 65% faster,
+ # preallocating the dict to len(seq); without
+ # preallocation it was only 25% faster. So the speed of
+ # this Python code is respectable. Just copying True into
+ # a local variable is responsible for a 7-8% speedup.
+ value = True
+ # XXX Should this perhaps look for _as_immutable?
+ # XXX If so, should use self.update(seq).
+ for key in seq:
+ data[key] = value
def __hash__(self):
if self._hashcode is None:
@@ -306,6 +308,16 @@
# BaseSet + operations requiring mutability; no hashing
+ def __init__(self, seq=None):
+ """Construct an immutable set from a sequence."""
+ self._data = data = {}
+ if seq is not None:
+ value = True
+ # XXX Should this perhaps look for _as_immutable?
+ # XXX If so, should use self.update(seq).
+ for key in seq:
+ data[key] = value
+
# In-place union, intersection, differences
def union_update(self, other):