Creating a List Using a Date as an Index

I have compiled a list that uses the list of dates as an index, for example:

>>> import datedlist
>>> import datetime
>>> dates = [datetime.date(2012,1,x) for x in range(2,6)]
>>> values = range(4,8)
>>> dates
[datetime.date(2012, 1, 2), datetime.date(2012, 1, 3), datetime.date(2012, 1, 4), datetime.date(2012, 1, 5)]
>>> dl = datedlist.DatedList(values, dates)
>>> dl
[4, 5, 6, 7]
>>> dl[datetime.date(2012,1,3)]
5

So far so good, but I also want to be able to use slicing (not extended slicing), for example (the following: not ) - this is the result I want):

>>> datedlist[datetime.date(2012,1,3):datetime.date(2012,1,4)]
[5, 6]

Here is my attempt (which obviously doesn't work):

class DatedList(list):

    def __init__(self, values, dates):
        self.dates = dates
        list.__init__(self, values)

    def __getitem__(self, date):
        if isinstance(date, slice):
            start = self.dates.index(slice[0])
            end = self.dates.index(slice[1])
            return [list.__getitem__(self, index) for index in range(start, end)]
        elif isinstance( date, datetime.date ) :
            index = self.dates.index(date)
            return list.__getitem__(self, index)
        elif isinstance(date, int):
            if date < 0:
                date += len(self)
            if date >= len(self):
                raise IndexError, "index out of range {}".format(date)
            return list.__getitem__(self, date)
        else:
            raise TypeError, "Invalid argument type."

Slice [0] and slice [1] are intended only to explain my intention. The value isinstance (date, int) is only available for debugging - it will be deleted for production code.

Here's the question : how can I implement slicing that uses datetime.date objects as indexes?

EDIT ( gnibblers): getlice ( , getlice ). ( isinstance-slice - ):

class DatedList(list):

    def __init__(self, values, dates):
        self.dates = dates
        list.__init__(self, values)

    def __contains__(self, date):
        return date in self.dates

    def __getslice__(self, fromdate, todate):
        i_from = self.get_index(fromdate)
        i_to = self.get_index(todate)
        print i_from, i_to
        return [list.__getitem__(self, i) for i in range(i_from, i_to)]

    def __getitem__(self, date):
        if isinstance(date, slice):
            pass
#            start = self.dates.index(slice[0])
#            end = self.dates.index(slice[1])
#            return [list.__getitem__(self, i) for i in range(start, end)]
        elif isinstance(date, datetime.date):
            index = self.get_index(date)
            return list.__getitem__(self, index)
        elif isinstance(date, int):
            if date < 0:
                date += len(self)
            if date >= len(self):
                raise IndexError, "index out of range {}".format(date)
            return list.__getitem__(self, date)
        else:
            raise TypeError, "Invalid argument type."

    def get_index(self, date):
        if date in self.dates:
            index = self.dates.index(date)
        elif date < self.dates[0]:
            index = 0
        elif date > self.dates[-1]:
            index = len(self.dates) - 1
        return index

:

>>> print dl[datetime.date(2012,1,3):datetime.date(2012,1,5)]
>>> None

-, getlice , . , getitem , , , , datetime.date . /EDIT

. -, , , , -, ( ):

• : [] :

  dl = DatedList(values, dates)
  value = dl[some_date]       # I want this to work
  value = dl.value(same_date) # I don't want this
  

• dict, , slicing.

• collection.Sequence, :

  TypeError: init ' ' list ', ' DatedList '