Re: Support for negative index values in array fetching

On 1/5/11 6:19 PM, Florian Pflug wrote:
>> Sorry, but It isn't too intuitive. Minimally for me. Why you don't
>> thinking about simple functions with only positive arguments. There
>> are only four combinations. I don't think we must have only one super
>> function.
>>
>> we need functionality for:
>>
>> a) get first n items
>> b) get items without last n items
>> c) get last n items
>> d) skip first n items
> Now you've moved the goalpost - the OP wanted to access individual
> elements, not slices! To support slices, a three-argument version
> of array_relative() would be required, with the signature
>
> array_relative(some_array anyarray, first int[], last int[])
>
> Your requirements (a) to (d) are then easily satisfied
>
> a) array_relative(ary, array[0], array[n-1])
> b) array_relative(ary, array[0], array[-n-1])
> c) array_relative(ary, array[-n], array[-1])
> d) array_relative(ary, array[n], array[-1])
>
> The individual function approach might be a tad more readable for
> one-dimensional arrays, but they don't scale well to the general
> case.
>
> Maybe the OP could comment on whether any of these solutions
> would fit his needs?
>
Hi,

(sorry for the late reply, got lost in my Inbox)

For my main use case I just needed the last element of the array, but I
could see myself needing a slice as well. (i.e. give me the last 5 items
in an array)

So in that sense yes, this would fit the bill.

Hannu Valtonen
Lead Software Architect
Technology Office
F-Secure Corporationhttp://www.F-Secure.com