class Set:
"""A Set is a collection of items with no particular ordering,
containing no dulicates."""
def __init__(self, *args):
self._dict = {}
for arg in args:
self.add(arg)
def __repr__(self):
import string
return "%s(%s)" % (self.__class__.__name__,
string.join(map(repr, self._dict.values()), ', '))
def extend(self, args):
"""Add several items at once."""
for arg in args:
self.add(arg)
def add(self, item):
"""Add one item to the set."""
self._dict[item] = item
def remove(self, item):
"""Remove an item from the set."""
del self._dict[item]
def contains(self, item):
"""Check whether the set contains a certain item."""
return self._dict.has_key(item)
# Higher performance member-test for python 2.0 and above
__contains__ = contains
def __getitem__(self, index):
"""Support the 'for item in set:' protocol."""
return self._dict.keys()[index]
def __len__(self):
"""Return the number of items in the set."""
return len(self._dict)
def items(self):
"""Return a list containing all items."""
return self._dict.keys()
# class Set()
