Negative array indicies and slice()

[Andrew Robinson]

On 10/30/2012 11:02 AM, Ian Kelly wrote:
> On Tue, Oct 30, 2012 at 10:14 AM, Ethan Furman<ethan at stoneleaf.us>  wrote:
>> File a bug report?
> Looks like it's already been wontfixed back in 2006:
>
> http://bugs.python.org/issue1501180
Thanks, IAN, you've answered the first of my questions and have been a 
great help.
(And yes, I was debugging interactive mode... I took a nap after writing 
that post, as I realized I had reached my 1 really bad post for the day... )

I at least I finally know why Python chooses to implement slice() as a 
separate object from tuple; even if I don't like the implications.

I think there are three main consequences of the present implementation 
of slice():

1) The interpreter code size is made larger with no substantial 
improvement in functionality, which increases debugging effort.
2) No protection against perverted and surprising (are you surprised?! I 
am) memory operation exists.
3) There is memory savings associated with not having garbage collection 
overhead.

D'Apriano mentioned the named values, start, stop, step in a slice() 
which are an API and legacy issue;  These three names must also be 
stored in the interpreter someplace.  Since slice is defined at the "C" 
level as a struct, have you already found these names in the source code 
(hard-coded), or are they part of a .py file associated with the 
interface to the "C" code?