slice notation as values?

[Duncan Booth]

Brian Beck wrote:

> Antoon Pardon wrote:
>> Will it ever be possible to write things like:
>> 
>>   a = 4:9
> 
> I made a silly recipe to do something like this a while ago, not that 
> I'd recommend using it. But I also think it wouldn't be too far-fetched
> to allow slice creation using a syntax like the above...
> 
> http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/415500
> 

Another possibility would be to make the slice type itself sliceable, then 
you could write things like:
>>> a = slice[4:9]
>>> a
slice(4, 9, None)

Sample implementation:

>>> class MetaSlice(object):
	def __getitem__(cls, item):
		return item
	def __init__(self, *args, **kw):
		return super(MetaSlice,self).__init__(self, *args, **kw)

	
>>> class Slice(slice):
	__metaclass__=MetaSlice

	
>>> Slice[2:3]
slice(2, 3, None)
>>> Slice[:3]
slice(None, 3, None)
>>> Slice[:3:-1]
slice(None, 3, -1)