How should I handle inclusive ranges in Python?

Question

I am working in a domain in which ranges are conventionally described inclusively. I have human-readable descriptions such as from A to B , which represent rang

Answer 1

I believe that the standard answer is to just use +1 or -1 everywhere it is needed.

You don't want to globally change the way slices are understood (that will break plenty of code), but another solution would be to build a class hierarchy for the objects for which you wish the slices to be inclusive. For example, for a list:

class InclusiveList(list):
    def __getitem__(self, index):
        if isinstance(index, slice):
            start, stop, step = index.start, index.stop, index.step
            if index.stop is not None:
                if index.step is None:
                    stop += 1
                else:
                    if index.step >= 0:
                        stop += 1
                    else:
                        if stop == 0: 
                            stop = None # going from [4:0:-1] to [4::-1] since [4:-1:-1] wouldn't work 
                        else:
                            stop -= 1
            return super().__getitem__(slice(start, stop, step))
        else:
            return super().__getitem__(index)

>>> a = InclusiveList([1, 2, 4, 8, 16, 32])
>>> a
[1, 2, 4, 8, 16, 32]
>>> a[4]
16
>>> a[2:4]
[4, 8, 16]
>>> a[3:0:-1]
[8, 4, 2, 1]
>>> a[3::-1]
[8, 4, 2, 1]
>>> a[5:1:-2]
[32, 8, 2]

Of course, you want to do the same with __setitem__ and __delitem__.

(I used a list but that works for any Sequence or MutableSequence.)