Slices time complexity

[Bartc]

"Steven D'Aprano" <steve+comp.lang.python at pearwood.info> wrote in message
news:555c225b$0$2769$c3e8da3$76491128 at news.astraweb.com...

> The mental gymnastics they go through to force the round peg of pass-by-
> sharing object semantics into the false dichotomy "pass-by-value versus
> pass-by-reference" is just crazy.
>
> One consequence of this is that the meaning of "call by value" depends on
> whether the value you are talking about is a boxed or unboxed value.
> Unboxed
> values are copied. Boxed values are not. Except that they are, if you
> understand that "the value" doesn't refer to the actual value, but to some
> hidden and implementation-dependent reference to the value.

I have a language where everything is boxed (the data that isn't boxed, has
to be before it can be manipulated).

But simple data such as small integers and floats are passed by value.
Bigger data is 'sort of' passed by reference, but not full reference (the
details are a bit messy, but if an object consists of two parts (A,B), then
a copy of descriptor A is passed, which contains a pointer to B. For small
scalars, the B part doesn't exist).

(A proper reference is available when passing arguments to functions:
a boxed pointer to (A,B) is constructed.)

However, I was so impressed with how (C)Python does things (working
exclusively with pointers, doing assignments by simply copying pointers, and
using reference counting to manage memory), that I'm experimenting with
letting my language work the same way. (Also then I can benchmark the two
more fairly.)

Then I get a little disillusioned when I find out in this thread that a
simple slice of an array actually copies every element! Since I currently
create a view (a good term I'd never come across before) for a slice, does
that mean I now also have to do what Python does?

(Currently, /assignments/ of arrays - and slices - involve a deep copy. But
for use as operands or passing as function arguments, only the lightweight
descriptor A is passed, the 'view' in the case of a slice.)

-- 
Bartc