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bug#24982: [External] : Re: bug#24982: 24.5; way to let Elisp reader ign
From: |
Drew Adams |
Subject: |
bug#24982: [External] : Re: bug#24982: 24.5; way to let Elisp reader ignore unreadable #(...) constructs |
Date: |
Sun, 13 Feb 2022 17:33:43 +0000 |
> > Provide a Boolean variable or a wrapper macro that has the effect of not
> > raising an error but just skipping over any unreadable #(...) construct.
>
> I assume you mean #<...> here?
No. I meant #(...). I wrote that twice.
But if you like you could extend this request
to some other - or to ALL - # reader syntax.
In that case, it would be good to be able to
specify just which syntaxes to ignore - e.g.,
have an option or defvar whose value is a list
that specifies which to ignore (e.g. in a
given context).
E.g. (from `i # TAB' in the Elisp manual):
##
#$
#'
#(
#@COUNT
#:
#N#
#N=
#^
> Anyway, there was some discussion about this in the context of the new
> readablep function and the `print-unreadable-function' variable. We
> could indeed introduce a new `read-unreadable-function' variable that's
> called when we encounter a #< instead of throwing an error (with no
> performance impact).
>
> Does anybody see any major downsides to doing that? We've been wary of
> allowing the users to customise the Emacs Lisp reader, but this seems
> like a very small thing. And it'd allow people to implement having
>
> #<marker in no buffer>
>
> read to (make-marker), etc, if they find that useful for some data
> structures.
>
> I had an extremely quick peek at this some time back, and it seemed
> pretty trivial to implement.
>
> Any opinions?
>
> --
> (domestic pets only, the antidote for overdose, milk.)
> bloggy blog:
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