C++ Logo


Advanced search

Re: [std-proposals] The Oxford variadic comma

From: Arthur O'Dwyer <arthur.j.odwyer_at_[hidden]>
Date: Thu, 29 Feb 2024 14:50:08 -0500
On Wed, Feb 28, 2024 at 2:14 PM Jan Schultke via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> The link
> https://eisenwave.github.io/cpp-proposals/oxford-variadic-comma.html
> remains valid and still points to the most recent version.

IMHO it's unfortunate that the grammar for *parameter-declaration-clause
<https://eel.is/c++draft/dcl.fct#nt:parameter-declaration-clause>* is so
mixed up at the moment. It has:
    parameter-declaration-list_opt ..._opt
    parameter-declaration-list , ...
where the first production handles all of
  void f()
  void f(int)
  void f(int x)
  void f(...)
  void f(int...) // deprecated, equivalent to f(int,...)
  void f(auto...)
  void f(int x...) // deprecated, equivalent to f(int,...)
  void f(auto x...) // deprecated, equivalent to f(auto,...)
It would be so much cleaner to rewrite the grammar as
    parameter-declaration-list , ...
    parameter-declaration-list ...
where the fourth production is deprecated and the first three are not.

I admit I'm thinking about messy grammar mainly because of how much time I
just put into studying the messy `friend` grammar and trying to disentangle
it for "Variadic Friends." There's certainly a lot of precedent for the
Committee's preferring "short and messy" over "long and clean," and
concretely in this case, sadly, I think it would distract and slow down the
paper if you asked to clean up the grammar at the same time.
Hmm, I wonder whether cleaning up this particular grammar could be done
editorially! That obviously wasn't on the table for `friend`, but might be
doable for something this small and self-contained.


Received on 2024-02-29 19:50:22