Re: Attaching context info to an error

[Alan Mackenzie <acm@muc.de>]

Hello, João.

On Fri, Dec 29, 2023 at 17:24:29 +0000, João Távora wrote:
> On Fri, Dec 29, 2023 at 5:19 PM Alan Mackenzie <acm@muc.de> wrote:

> > Talk about "generic functions" and "proper objects" makes me worried
> > indeed.  The Emacs error handling must work fully right from early
> > bootstrap, i.e. when no Lisp has yet been loaded.  The "proper object"
> > for this is a list, of defined structure.

> It's indistinguishable from a cons, which is bad for many reasons
> explained at length.

But it's a good choice for early bootstrap.  How about dealing with
those reasons in other ways rather than using not-yet-existent data
structures.

> Weren't you involved in "symbol-with-pos"?

I developped them, yes.

> It's a similar object with a unique type.

Similar to what?

> So it's going to need more arguments than just being scared of generic
> functions.

There's no fear involved at all.  cl-lib is an exceptionally
controversial part of Emacs, as we established two or three weeks ago.
It's poorly documented, and likely buggy.  It's not something to be
moved to the centre of the Emacs Lisp machine.

> Noone is advocating for calling generic functions from C or preloading
> them, etc, so don't worry about it.

That's got no connection with what I wrote.  What I'm asking you to
confirm is that you're not contemplating introducing error handling
machinery which, during bootstrap, will only work after Lisp code has
been loaded.

-- 
Alan Mackenzie (Nuremberg, Germany).