Re: Question on the behavior of length()

[Ed Morton]

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.