Re: Why "symbol's value" error about a list?

[Tim Cross <theophilusx@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 3814 bytes --]

It seems there are two issues here - they are not completely separate, but
do seem to be distinct and probably need to be addressed in two steps.

If the statement

> Count me as one of those "some of us".  Echoing Lisp code
> should do just that - no fiddling to "prettify" apostrophe to
> curly quote etc.

is correct, then I would agree it was a bad design decision. The *Messages*
buffer should display lisp code exactly as it is read and not try to
'prettify' it.

The second issue seems to be more about how to make the error message more
informative. I suspect this is a much harder problem to resolve. I don't
know what the right solution is for that, but I do know that I would have
more chance of recognising my error if the message displayed in the buffer
displays the lisp code exactly as it was read by the reader.

Tim


On 6 February 2018 at 15:13, Eli Zaretskii <eliz@gnu.org> wrote:

> > Date: Mon, 5 Feb 2018 13:46:38 -0800 (PST)
> > From: Drew Adams <drew.adams@oracle.com>
> > Cc: Eli Zaretskii <eliz@gnu.org>, npostavs@users.sourceforge.net,
> >         emacs-devel@gnu.org
> >
> > > The error message given out is:
> > >     Symbol's value as variable is void: ’bar
> >
> > That was the old, and legitimate, error message, yes.  It
> > accurately describes what is really going on (as you describe
> > well, below).
> >
> > Now the message is instead (invalid-read-syntax "strange quote"
> > "’").  Is that better?
>
> I think it's somewhat better, because it talks about "strange quote",
> which is a hint for the user about the actual problem.
>
> > I suggested that the variable name be enclosed in `...'.  That
> > would make the original message clearer, I think:
> >
> >   Symbol's value as variable is void: `’bar'
>
> That might make things even more confusing, because the text actually
> displayed will be this:
>
>     Symbol’s value as variable is void: ‘’bar’
>
> which loses all hints of what is being quoted here.
>
> > > This is a result of the change in `message', silently to convert ' to a
> > > curly quote, by default.  Some of us were unhappy at this change and
> > > protested against it.
> >
> > Count me as one of those "some of us".  Echoing Lisp code
> > should do just that - no fiddling to "prettify" apostrophe to
> > curly quote etc.
>
> That ship has sailed two Emacs releases ago.  We are trying to fix the
> fallout.
>
> And strange quotes is only one situation where confusingly similar
> characters can be presented in error messages, making it hard for
> users to spot the real problem.  We are trying to find ways of making
> such "typos" more evident in error messages.
>
> > The error is using a symbol as a variable, when it is not
> > defined as a variable.  Which is exactly what the original
> > error message said.
> >
> > That's the LISP error.  Is there a _user error_ here?
> > Yes, it's the mistake of copying and pasting what was
> > printed in *Messages*.
> >
> > That user mistake is excusable.  And we would want to
> > inform the user about it, if we can't prevent it.  But
> > changing Lisp read syntax to guess what might be the
> > most helpful thing to tell a user here is NOT the solution.
>
> The issue is what _would_ be a helpful message in these cases.  You
> are just saying what should _not_ be done (repeatedly), but that
> doesn't advance us towards the solution.
>
> > Should this Lisp syntax change be reverted?  That's the
> > question being discussed here.
>
> No, that's only part of the question.  The other, no less important
> part is if we revert that change, how to make the confusing error
> message less so and more helpful in understanding the user error.
>
>


-- 
regards,

Tim

--
Tim Cross

[-- Attachment #2: Type: text/html, Size: 5199 bytes --]