From: Alan Mackenzie <acm@muc.de>
To: Stefan Monnier <monnier@IRO.UMontreal.CA>
Cc: emacs-devel@gnu.org
Subject: Re: Can't M-x compile-defun `edebug' because dynamic variables are falsely taken as lexical.
Date: Wed, 4 Jan 2017 13:39:48 +0000 [thread overview]
Message-ID: <20170104133948.GA7373@acm.fritz.box> (raw)
In-Reply-To: <jwv1swj4yao.fsf-monnier+Inbox@gnu.org>
Hello, Stefan.
On Tue, Jan 03, 2017 at 04:48:15PM -0500, Stefan Monnier wrote:
> > It looks like you've already done that, possibly on 2015-10-29. Looking
> > at the source (now I know what to look for), eval-sexp-add-defvars is
> > also in Emacs 25.1's source for compile-defun.
> Oh, indeed. Not sure why you're seeing what you're seeing, then.
> At least on Emacs's master branch I can't seem to reproduce your problem
> (don't have a fresh emacs-25 build to try it right now).
For what it's worth, I can't reproduce the problem any more. I must
have got my Emacs 25.1 into a strange state, somehow.
> > , so the question becomes why is setting the declared_special flag done
> > inside the "if (CONSP (tail))" rather than outside? I.e. why is it only
> > done when a variable has an initialisation?
> Because this code is only relevant when you evaluate (defvar <foo>),
> whereas here we're not evaluating it, we're only processing it for the
> byte-compiler.
Understood. Thanks.
> There's also the important difference that a (defvar <foo>) only
> has effect for the code in the same file rather than having a global
> effect, so you can do (defvar toto) and then use `toto` as
> a dynamically-scoped variable in your file without wreaking havoc in all
> other files which happen to also use `toto` as a (lexical) variable.
Ouch! There seems to be a clash between symbols (which are global,
dynamic) and lexical variables (which are local and "invisible"): the
only way to mark a variable as lexical is at the global level.
However, I'm seeing something else strange (still on 25.1). I do this:
(i) M-x load-library edebug.
(ii) visit edebug.el.
(iii) instrument `edebug' for edebugging (yes, I know ;-).
(iv) M-: (edebug).
(v) step through the function to just after the let bindings.
(vi) e (special-variable-p 'edebug-breakpoints).
This last returns nil. This suggests edebug-breakpoints has been bound
as a lexical variable, rather than a dynamic one. (There is a defvar
for it earlier in the file.) This is surely not right.
What is going on here? Is it, perhaps, a bug?
However, edebug.elc still seems to work, though I haven't successfully
mananged to run `edebug' recently.
> Stefan
--
Alan Mackenzie (Nuremberg, Germany).
next prev parent reply other threads:[~2017-01-04 13:39 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-03 14:14 Can't M-x compile-defun `edebug' because dynamic variables are falsely taken as lexical Alan Mackenzie
2017-01-03 18:35 ` Stefan Monnier
2017-01-03 21:32 ` Alan Mackenzie
2017-01-03 21:48 ` Stefan Monnier
2017-01-04 13:39 ` Alan Mackenzie [this message]
2017-01-04 15:23 ` Stefan Monnier
2017-01-04 20:04 ` Alan Mackenzie
2017-01-04 21:49 ` Stefan Monnier
2017-01-04 22:02 ` Alan Mackenzie
2017-01-04 22:26 ` Stefan Monnier
2017-01-04 22:44 ` Drew Adams
2017-01-05 10:54 ` Alan Mackenzie
2020-02-13 16:42 ` Drew Adams
2020-02-13 20:02 ` Stefan Monnier
2020-02-13 20:43 ` Drew Adams
2020-02-13 22:09 ` Stefan Monnier
2020-02-14 1:07 ` Drew Adams
2020-02-14 2:24 ` Stefan Monnier
2020-02-14 17:25 ` Drew Adams
2020-02-14 19:19 ` Stefan Monnier
2020-02-17 18:23 ` Drew Adams
2020-02-13 22:11 ` Stefan Monnier
2020-02-14 1:13 ` Drew Adams
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