Re: bug in simplify_shallow

* Ruud H.G. van Tol [2023-08-27 15:42]:
> 
> On 2023-08-27 14:58, Bill Allombert wrote:
> > [...]to be honest I did not remember that listput returned x and it is
> > not explicitly documented
> 
> ? ??listput
> listput( list,x,{n}):
> 
>    Sets the n-th element of the list list (which must be of type t_LIST)
> equal to x. If n is omitted, or greater than the list length, appends x. The
> function returns the inserted element.
> 
> So "returns the inserted element".

What "the inserted element" means is ambiguous in the context of PARI's
memory model. What the implementation does is return a direct pointer to
the new list entry, that inserted element being a clone of the input x.

What Bill and I suggested was to return "a copy of the inserted element"
instead. I don't really see a scenario where this would break
compatibility ... except this would make insertion about twice slower,
even in cases where the returned value is ignored.

Cheers,

    K.B.
-- 
Pr. Karim Belabas, U. Bordeaux, Vice-président en charge du Numérique
Institut de Mathématiques de Bordeaux UMR 5251 - (+33) 05 40 00 29 77
http://www.math.u-bordeaux.fr/~kbelabas/