Negative array indicies and slice()

[Andrew Robinson]

On 10/29/2012 10:53 PM, Michael Torrie wrote:
> On 10/29/2012 01:34 PM, Andrew Robinson wrote:
>> No, I don't think it big and complicated.  I do think it has timing
>> implications which are undesirable because of how *much* slices are used.
>> In an embedded target -- I have to optimize; and I will have to reject
>> certain parts of Python to make it fit and run fast enough to be useful.
> Since you can't port the full Python system to your embedded machine
> anyway, why not just port a subset of python and modify it to suit your
> needs right there in the C code.  It would be a fork, yes,
You're exactly right;  That's what I *know* I am faced with.

>    Without a libc, an MMU on the CPU, and a kernel, it's not going to just compile and run.
I have libc.  The MMU is a problem; but the compiler implements the 
standard "C" math library; floats, though, instead of doubles.  That's 
the only problem -- there.
>   What you want with slicing behavior changes has no
> place in the normal cPython implementation, for a lot of reasons.  The
> main one is that it is already possible to implement what you are
> talking about in your own python class, which is a fine solution for a
> normal computer with memory and CPU power available.
If the tests I outlined in the previous post inaccurately describe a 
major performance improvement and at least a modest code size reduction; 
or will *often* introduce bugs -- I *AGREE* with you.

Otherwise, I don't.  I don't think wasting extra CPU power is a good 
thing -- Extra CPU power can always be used by something else....

I won't belabor the point further.  I'd love to see a counter example to 
the specific criteria I just provided to IAN -- it would end my quest; 
and be a good reference to point others to.