Possible improvement to slice opperations.

Patrick Maupin pmaupin at gmail.com
Tue Sep 6 03:42:27 CEST 2005


> No one has yet explained the reasoning (vs the mechanics) of the
> returned value of the following.
>
>     L = range(10)
>     L[3::-1]
>
> So far every attempt to explain it has either quoted the documents which
> don't address that particular case, or assumed I'm misunderstanding
> something, or implied it isn't neccisary to do.
>
> It's quite easy to get me to change my mind on something, just show me a
> convincing explanation and I will. :)

Once I saw this, I was surprised, because slices currently work exactly
like I would and do expect on this example, so I now have to admit that
I didn't read your original post fully and carefully.  I have gone back
to look to figure out what you don't like and what you want, and I am
very surprised.

To me, your way reeks of black magic -- if there is a sign on the
stride, then strange and wondrous transformations happen.  I think it
is conceptually (and probably programatically) much simpler the way it
is.

In any case, you asked for a rationale.  I'll give you mine:

>>> L = range(10)
>>> L[3:len(L):-1] == [L[i] for i in range(3,len(L),-1)]
True
>>>

If you manage somehow to hange that 'True' to a 'False', I'll
personally be extremely unhappy.

Regards,
Pat




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