GNU bug report logs - #18005
24.4.50; In Emacs manual, tell users how to enter debugger for `user-error' errors

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Drew Adams <drew.adams <at> oracle.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.4.50; In Emacs manual, tell users how to enter debugger for
 `user-error' errors
Date: Sat, 12 Jul 2014 10:59:57 -0700 (PDT)

The only hint about how to make Emacs enter the debugger for errors
deemed `user-error' is this mention, buried in the
`debug-ignored-errors' entry of the Elisp manual:

     The normal value of this variable includes `user-error', as well
     as several errors that happen often during editing but rarely
     result from bugs in Lisp programs.  However, "rarely" is not
     "never"; if your program fails with an error that matches this
     list, you may try changing this list to debug the error.  The
     easiest way is usually to set `debug-ignored-errors' to `nil'.

(FWIW, wrt this text: Is it really necessary to point out that
users can want to enter the debugger for other reasons that
tracking down a Lisp bug?)

It should be made *obvious* to users, in the *Emacs* manual, how to make
the debugger open for so-called "user errors".

In particular, some mention of how to do this should be added to any
descriptions of `debug-on-error' and `toggle-debug-on-error'.  Yes,
*especially* since these have NO effect on this.  Users will try these
and not understand how to get what they want in this regard.  Here
is one proof: http://superuser.com/q/782313/250462.

(Hard to believe that something presumably designed with end users in
mind would not be documented wrt how to access the debugger.  Of
course, `user-error' has NOTHING to do with user errors anyway...)

In GNU Emacs 24.4.50.1 (i686-pc-mingw32)
 of 2014-06-28 on ODIEONE
Bzr revision: 117431 rgm <at> gnu.org-20140628015517-eku6hj8mpgcvfnso
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/snapshot/trunk
 --enable-checking=yes,glyphs 'CFLAGS=-O0 -g3'
 LDFLAGS=-Lc:/Devel/emacs/lib 'CPPFLAGS=-DGC_MCHECK=1
 -Ic:/Devel/emacs/include''

Message #8 received at 18005 <at> debbugs.gnu.org (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: 18005 <at> debbugs.gnu.org
Subject: Re: bug#18005: 24.4.50;
 In Emacs manual, tell users how to enter debugger for `user-error'
 errors
Date: Sat, 12 Jul 2014 21:35:31 -0400

The whole point of introducing user-error was so that uninteresting
errors will not trigger the debugger. I see no need to mention in the
*Emacs* manual how to get round this.

(I am not going to get into a big debate about this.)

Message #13 received at 18005 <at> debbugs.gnu.org (full text, mbox):

From: Drew Adams <drew.adams <at> oracle.com>
To: Glenn Morris <rgm <at> gnu.org>, 18005 <at> debbugs.gnu.org
Subject: RE: bug#18005: 24.4.50; In Emacs manual, tell users how to enter
 debugger for `user-error' errors
Date: Sat, 12 Jul 2014 19:41:13 -0700 (PDT)

> The whole point of introducing user-error was so that uninteresting
> errors will not trigger the debugger. I see no need to mention in the
> *Emacs* manual how to get round this.

"The whole point" should be to _let_ users not be bothered entering
the debugger for uninteresting errors.  That's reasonable behavior.
*Enabling* that behavior is positive.  Forcing it would be
counterproductive, as is not making clear what it is that controls it.

Not to mention the fact that what constitutes an "uninteresting
error" is not something fixed once and for all for everyone.  It
can change, depending on the context.  A user might well want to
take a look under the covers using the debugger in some context.
(The user who just now asked how to do it, for instance.)

> (I am not going to get into a big debate about this.)

No one asked you to.

Message #16 received at 18005 <at> debbugs.gnu.org (full text, mbox):

From: Richard Stallman <rms <at> gnu.org>
To: Drew Adams <drew.adams <at> oracle.com>
Cc: rgm <at> gnu.org, 18005 <at> debbugs.gnu.org
Subject: Re: bug#18005: 24.4.50;
 In Emacs manual, tell users how to enter debugger for `user-error'
 errors
Date: Sun, 13 Jul 2014 17:54:24 -0400

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

    "The whole point" should be to _let_ users not be bothered entering
    the debugger for uninteresting errors.  That's reasonable behavior.
    *Enabling* that behavior is positive.  Forcing it would be
    counterproductive, as is not making clear what it is that controls it.

I agree.

    Not to mention the fact that what constitutes an "uninteresting
    error" is not something fixed once and for all for everyone.  It
    can change, depending on the context.  A user might well want to
    take a look under the covers using the debugger in some context.
    (The user who just now asked how to do it, for instance.)

I have several times wanted to enter the debugger because a
program triggered one of these errors which usually is caused by
bad user input.  So I used the feature to enable that.

There should continue to be a convenient feature to enable that.

-- 
Dr Richard Stallman
President, Free Software Foundation
51 Franklin St
Boston MA 02110
USA
www.fsf.org  www.gnu.org
Skype: No way! That's nonfree (freedom-denying) software.
  Use Ekiga or an ordinary phone call.

Message #19 received at 18005 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Drew Adams <drew.adams <at> oracle.com>
Cc: 18005 <at> debbugs.gnu.org
Subject: Re: bug#18005: 24.4.50;
 In Emacs manual, tell users how to enter debugger for `user-error'
 errors
Date: Fri, 29 Apr 2016 23:51:23 +0200

Drew Adams <drew.adams <at> oracle.com> writes:

> The only hint about how to make Emacs enter the debugger for errors
> deemed `user-error' is this mention, buried in the
> `debug-ignored-errors' entry of the Elisp manual:
>
>      The normal value of this variable includes `user-error', as well
>      as several errors that happen often during editing but rarely
>      result from bugs in Lisp programs.  However, "rarely" is not
>      "never"; if your program fails with an error that matches this
>      list, you may try changing this list to debug the error.  The
>      easiest way is usually to set `debug-ignored-errors' to `nil'.
>
> (FWIW, wrt this text: Is it really necessary to point out that
> users can want to enter the debugger for other reasons that
> tracking down a Lisp bug?)
>
> It should be made *obvious* to users, in the *Emacs* manual, how to make
> the debugger open for so-called "user errors".

I think this belongs in the elisp manual, and the explanation there is
fine.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Message #24 received at 18005 <at> debbugs.gnu.org (full text, mbox):

From: Drew Adams <drew.adams <at> oracle.com>
To: Lars Ingebrigtsen <larsi <at> gnus.org>
Cc: 18005 <at> debbugs.gnu.org
Subject: RE: bug#18005: 24.4.50; In Emacs manual, tell users how to enter
 debugger for `user-error' errors
Date: Fri, 29 Apr 2016 15:53:57 -0700 (PDT)

> > The only hint about how to make Emacs enter the debugger for errors
> > deemed `user-error' is this mention, buried in the
> > `debug-ignored-errors' entry of the Elisp manual:
> >
> >      The normal value of this variable includes `user-error', as well
> >      as several errors that happen often during editing but rarely
> >      result from bugs in Lisp programs.  However, "rarely" is not
> >      "never"; if your program fails with an error that matches this
> >      list, you may try changing this list to debug the error.  The
> >      easiest way is usually to set `debug-ignored-errors' to `nil'.
> >
> > (FWIW, wrt this text: Is it really necessary to point out that
> > users can want to enter the debugger for other reasons that
> > tracking down a Lisp bug?)
> >
> > It should be made *obvious* to users, in the *Emacs* manual, how to make
> > the debugger open for so-called "user errors".
> 
> I think this belongs in the elisp manual, and the explanation there is
> fine.

I disagree (like RMS).  How to enter the debugger, including for
"user" errors, is not information we should bury.  It should be
mentioned in the Emacs manual, with a link to the Elisp manual
for more info.

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