Re: Question on the behavior of length()

[Wolfgang Laun]

Call it x["tos"] and x["doc"] to avoid me being confused and having to
remember what is what.
-W

On Mon, 11 Dec 2023 at 13:38, Ed Morton <mortoneccc@comcast.net> wrote:

> Just a suggestion regarding calling `length()` for push()/pop() stack
> operations:
>
> On 12/10/2023 8:18 AM, Christian Schmidt wrote:
> > Hi all,
> >
> > First of all I'd like to state that I do not consider the following
> > necessarily a bug; however I'd like to discuss the current
> > implementation, and have not found a better place to do so.
> >
> > My issue is that I can't use
> >
> > x[length(x)] = y
> >
> > e.g. to emulate to push to a stack, without explicitly converting x
> > into an array first, e.g. by "delete x".
>
> No need to call `length(x)` for every push()/pop(), you can implement a
> stack by storing it's top index in `x[0]` (or some other unused,
> probably negative, index instead if you prefer):
>
>       function push(x,y) { x[++x[0]] = y }
>       function pop(x) { delete x[x[0]--] }
>
> As well as not having the problem you described that also allows you to
> use other unused indices to store other attributes about the stack, e.g.
> a description like `x[-1] = "this is a stack of connection requests"`,
> which you couldn't do if you were relying on `length(x)` to tell you the
> index of the top of the stack.
>
> Regards,
>
>      Ed.
>


-- 
Wolfgang Laun