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    <p>An indexed list class:</p> <pre><code>class IndexedList(list): def __init__(self, items, attrs): super(IndexedList,self).__init__(items) # do indexing self._attrs = tuple(attrs) self._index = {} _add = self._addindex for obj in self: _add(obj) def _addindex(self, obj): _idx = self._index for attr in self._attrs: _idx[getattr(obj, attr)] = obj def _delindex(self, obj): _idx = self._index for attr in self._attrs: try: del _idx[getattr(obj,attr)] except KeyError: pass def __delitem__(self, ind): try: obj = list.__getitem__(self, ind) except (IndexError, TypeError): obj = self._index[ind] ind = list.index(self, obj) self._delindex(obj) return list.__delitem__(self, ind) def __delslice__(self, i, j): for ind in xrange(i,j): self.__delitem__(ind) def __getitem__(self, ind): try: return self._index[ind] except KeyError: return list.__getitem__(self, ind) def __getslice__(self, i, j): return IndexedList(list.__getslice__(self, i, j)) def __setitem__(self, ind, new_obj): try: obj = list.__getitem__(self, ind) except (IndexError, TypeError): obj = self._index[ind] ind = list.index(self, obj) self._delindex(obj) self._addindex(new_obj) return list.__setitem__(ind, new_obj) def __setslice__(self, i, j, newItems): _get = self.__getitem__ _add = self._addindex _del = self._delindex newItems = list(newItems) # remove indexing of items to remove for ind in xrange(i,j): _del(_get(ind)) # add new indexing if isinstance(newList, IndexedList): self._index.update(newList._index) else: for obj in newList: _add(obj) # replace items return list.__setslice__(self, i, j, newList) def append(self, obj): self._addindex(obj) return list.append(self, obj) def extend(self, newList): newList = list(newList) if isinstance(newList, IndexedList): self._index.update(newList._index) else: _add = self._addindex for obj in newList: _add(obj) return list.extend(self, newList) def insert(self, ind, new_obj): # ensure that ind is a numeric index try: obj = list.__getitem__(self, ind) except (IndexError, TypeError): obj = self._index[ind] ind = list.index(self, obj) self._addindex(new_obj) return list.insert(self, ind, new_obj) def pop(self, ind=-1): # ensure that ind is a numeric index try: obj = list.__getitem__(self, ind) except (IndexError, TypeError): obj = self._index[ind] ind = list.index(self, obj) self._delindex(obj) return list.pop(self, ind) def remove(self, ind_or_obj): try: obj = self._index[ind_or_obj] ind = list.index(self, obj) except KeyError: ind = list.index(self, ind_or_obj) obj = list.__getitem__(self, ind) self._delindex(obj) return list.remove(self, ind) </code></pre> <p>which can be used as:</p> <pre><code>class Child(object): def __init__(self, id, name): self.id = id self.name = name class Teacher(object): def __init__(self, id, name): self.id = id self.name = name class Classroom(object): def __init__(self, children, teachers): self.children = IndexedList(children, ('id','name')) self.teachers = IndexedList(teachers, ('id','name')) classroom = Classroom([Child('389','pete')], [Teacher('829','bob')]) print classroom.children[0].name # -&gt; pete classroom.children.append(Child('2344','joe')) print len(classroom.children) # -&gt; 2 print classroom.children[1].name # -&gt; joe print classroom.children['joe'].id # -&gt; 2344 print classroom.children['2344'].name # -&gt; joe p = classroom.children.pop('pete') print p.name # -&gt; pete print len(classroom.children) # -&gt; 1 </code></pre> <p><strong>Edit:</strong> I had made a mistake in some of the exception-handling (catching KeyError instead of IndexError); it is fixed. I will add some unit-testing code. If you run into any further errors, please let me know!</p>
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    1. COThis is great. Did you just whip this up?
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    2. COYes, so beware - not fully tested! Also, the indexing does not yet properly handle duplicate field values - adding Child('1234','bob') and Child('2550','bob') will blow its mind. self._index should properly be a dict of list, which then needs some extra code in _delindex to remove the correct object; __getitem__ should return just the first value, and there should be a findAll method which returns the entire list; also I am thinking about separate per-attribute indexes such that you could do classroom.children[id=3] while defaulting to search-on-all-attributes.
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    3. COAdded __contains__ and get functions. Modified __getitem__ to return keyerror. Created a gist here: https://gist.github.com/895134
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