Re: bug#1406: backward-up-list reports scan error incorrectly?

Re: bug#1406: backward-up-list reports scan error incorrectly?

[Alan Mackenzie]

Hi, Xah!

> > though, isn't this something easy to fix?

> No, because it isn't a bug.  It's the way the function is meant to work.
> If there is a bug, it's that the doc-string (and maybe the elisp manual,
> I haven't looked) is vague and incomplete.

I've amended the Emacs manual (.../doc/emacs/programs.texi) and the doc
strings of `backward-up-list' and several similar functions
(.../lisp/emacs-lisp/lisp.el).

If you're interested, have a look at the changes in
<http://cvs.savannah.gnu.org/viewvc/emacs/?root=emacs>.

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: bug#1406: backward-up-list reports scan error incorrectly?

[xah lee]

On Nov 27, 4:19 am, Alan Mackenzie <a...@muc.de> wrote:
 > Hi, Xah!
 >
 > > > though, isn't this something easy to fix?
 > > No, because it isn't a bug.  It's the way the function is meant  
to work.
 > > If there is a bug, it's that the doc-string (and maybe the elisp  
manual,
 > > I haven't looked) is vague and incomplete.
 >
 > I've amended the Emacs manual (.../doc/emacs/programs.texi) and  
the doc
 > strings of `backward-up-list' and several similar functions
 > (.../lisp/emacs-lisp/lisp.el).
 >
 > If you're interested, have a look at the changes in
 > <http://cvs.savannah.gnu.org/viewvc/emacs/?root=emacs>.

Thanks Alan.

I'd rather hope for a fix instead of change wording to reflect  
current situation.

You argued in bug list that the issue is not simple essentially due  
to the fact that straight quote chars are not matching pairs.

That is true, but i think given today's tech and computing power, we  
can over come this. Just assume that double quotes in the source code  
are matched, since they are most of the time. In the few cases when  
the backward-up-list went to the wrong place due to un-matched double  
quote, i think that's ok. (as opposed to, it stops dead and utter a  
beep.)

alternatively, if the cursor is inside double quote, then issue a  
warning in the messag area that the result may not be correct.

Also, since this works in text-mode, so apparently this can work. A  
implementation is to temporarily switch to that mode, do the cursor  
move, then switch back. Or temp set the syntax table to whatever chat  
that made text-mode work and emacs-lisp-mode not work.

In general, my feeling is that moving around nested pairs is not a  
some insurmountable issue, that given today's technology and  
software, it seems wimpy to tell users that backward-up-list won't  
work if it's inside double quotes. Much complex problems are solved  
today in emacs, in other IDEs, etc.

Just my opinions. Thanks.

   Xah
∑ http://xahlee.org/

☄



On Nov 27, 2008, at 4:19 AM, Alan Mackenzie wrote:

Hi, Xah!

>> though, isn't this something easy to fix?

> No, because it isn't a bug.  It's the way the function is meant to  
> work.
> If there is a bug, it's that the doc-string (and maybe the elisp  
> manual,
> I haven't looked) is vague and incomplete.

I've amended the Emacs manual (.../doc/emacs/programs.texi) and the doc
strings of `backward-up-list' and several similar functions
(.../lisp/emacs-lisp/lisp.el).

If you're interested, have a look at the changes in
<http://cvs.savannah.gnu.org/viewvc/emacs/?root=emacs>.

-- 
Alan Mackenzie (Nuremberg, Germany).

☄

Re: bug#1406: backward-up-list reports scan error incorrectly?

[Alan Mackenzie]

Hi, Xah.

On Thu, Nov 27, 2008 at 07:56:17AM -0800, xah lee wrote:
> On Nov 27, 4:19 am, Alan Mackenzie <a...@muc.de> wrote:
> > Hi, Xah!

> > > > though, isn't this something easy to fix?
> > > No, because it isn't a bug.  It's the way the function is meant  to
> > > work.  If there is a bug, it's that the doc-string (and maybe the
> > > elisp  manual, I haven't looked) is vague and incomplete.

> > I've amended the Emacs manual (.../doc/emacs/programs.texi) and  the
> > doc strings of `backward-up-list' and several similar functions
> > (.../lisp/emacs-lisp/lisp.el).

> > If you're interested, have a look at the changes in
> > <http://cvs.savannah.gnu.org/viewvc/emacs/?root=emacs>.

> Thanks Alan.

> I'd rather hope for a fix instead of change wording to reflect  
> current situation.

Again, there isn't a bug, so there's nothing to fix.  What I think you're
saying is that you'd prefer C-M-u to do something a bit different; or,
put another way, you want a different function.

Personally, I like being able to use the list commands inside a comment
or string.

Don't forget that the list commands are also used a lot as
almost-primitive functions in other lisp code (they're certainly used a
lot in CC Mode), and redefining these the way you suggest would slow down
other code, possibly by a lot.

> You argued in bug list that the issue is not simple essentially due  
> to the fact that straight quote chars are not matching pairs.

> That is true, but i think given today's tech and computing power, we  
> can over come this. Just assume that double quotes in the source code  
> are matched, since they are most of the time. In the few cases when  
> the backward-up-list went to the wrong place due to un-matched double  
> quote, i think that's ok. (as opposed to, it stops dead and utter a  
> beep.)

The stopping dead is due to it not finding an enclosing paren.

> alternatively, if the cursor is inside double quote, then issue a  
> warning in the messag area that the result may not be correct.

Why don't you write the function you want?  Then submit it to
emacs-devel@gnu.org, and it could well become an option in Emacs 24.

You have to decide what "inside a string" means.  It could be as simple
as the text at point being fontified with font-lock-string-face.  Or,
maybe you'd want to scan from the beginning of buffer to check this.
`parse-partial-sexp' is your friend here.

> Also, since this works in text-mode, so apparently this can work. A  
> implementation is to temporarily switch to that mode, do the cursor  
> move, then switch back. Or temp set the syntax table to whatever chat  
> that made text-mode work and emacs-lisp-mode not work.

That's another way you could do it.  In text mode, I don't think there
are any string characters defined (we're talking about its "syntax table"
here).  So if you did this (switching temporarily to Text Mode) in Elisp
mode, you'd just get a very crude interpretation of parens.  It might be
what you want, it might not.

> In general, my feeling is that moving around nested pairs is not a  
> some insurmountable issue, that given today's technology and  
> software, it seems wimpy to tell users that backward-up-list won't  
> work if it's inside double quotes. Much complex problems are solved  
> today in emacs, in other IDEs, etc.

No, it's certainly surmountable.  But first you've got to decide what you
want, then you've got to do the surmounting.

> Just my opinions. Thanks.

No problem!

>   Xah

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: bug#1406: backward-up-list reports scan error incorrectly?

[xah lee]

> Personally, I like being able to use the list commands inside a  
> comment
> or string.
>
> Don't forget that the list commands are also used a lot as
> almost-primitive functions in other lisp code (they're certainly  
> used a
> lot in CC Mode), and redefining these the way you suggest would  
> slow down
> other code, possibly by a lot.

I see. great info.

Doh, i thought i was replying to the bug list. My prev post wast  
intended for the bug list so that that the communication is unbroken  
there but didn't notice it just went to help.gnu.emacs. but anyway,  
you probably right.

   Xah
∑ http://xahlee.org/

☄

On Nov 27, 2008, at 2:09 PM, Alan Mackenzie wrote:

Hi, Xah.

On Thu, Nov 27, 2008 at 07:56:17AM -0800, xah lee wrote:
> On Nov 27, 4:19 am, Alan Mackenzie <a...@muc.de> wrote:
>> Hi, Xah!

>>>> though, isn't this something easy to fix?
>>> No, because it isn't a bug.  It's the way the function is meant  to
>>> work.  If there is a bug, it's that the doc-string (and maybe the
>>> elisp  manual, I haven't looked) is vague and incomplete.

>> I've amended the Emacs manual (.../doc/emacs/programs.texi) and  the
>> doc strings of `backward-up-list' and several similar functions
>> (.../lisp/emacs-lisp/lisp.el).

>> If you're interested, have a look at the changes in
>> <http://cvs.savannah.gnu.org/viewvc/emacs/?root=emacs>.

> Thanks Alan.

> I'd rather hope for a fix instead of change wording to reflect
> current situation.

Again, there isn't a bug, so there's nothing to fix.  What I think  
you're
saying is that you'd prefer C-M-u to do something a bit different; or,
put another way, you want a different function.

Personally, I like being able to use the list commands inside a comment
or string.

Don't forget that the list commands are also used a lot as
almost-primitive functions in other lisp code (they're certainly used a
lot in CC Mode), and redefining these the way you suggest would slow  
down
other code, possibly by a lot.

> You argued in bug list that the issue is not simple essentially due
> to the fact that straight quote chars are not matching pairs.

> That is true, but i think given today's tech and computing power, we
> can over come this. Just assume that double quotes in the source code
> are matched, since they are most of the time. In the few cases when
> the backward-up-list went to the wrong place due to un-matched double
> quote, i think that's ok. (as opposed to, it stops dead and utter a
> beep.)

The stopping dead is due to it not finding an enclosing paren.

> alternatively, if the cursor is inside double quote, then issue a
> warning in the messag area that the result may not be correct.

Why don't you write the function you want?  Then submit it to
emacs-devel@gnu.org, and it could well become an option in Emacs 24.

You have to decide what "inside a string" means.  It could be as simple
as the text at point being fontified with font-lock-string-face.  Or,
maybe you'd want to scan from the beginning of buffer to check this.
`parse-partial-sexp' is your friend here.

> Also, since this works in text-mode, so apparently this can work. A
> implementation is to temporarily switch to that mode, do the cursor
> move, then switch back. Or temp set the syntax table to whatever chat
> that made text-mode work and emacs-lisp-mode not work.

That's another way you could do it.  In text mode, I don't think there
are any string characters defined (we're talking about its "syntax  
table"
here).  So if you did this (switching temporarily to Text Mode) in Elisp
mode, you'd just get a very crude interpretation of parens.  It might be
what you want, it might not.

> In general, my feeling is that moving around nested pairs is not a
> some insurmountable issue, that given today's technology and
> software, it seems wimpy to tell users that backward-up-list won't
> work if it's inside double quotes. Much complex problems are solved
> today in emacs, in other IDEs, etc.

No, it's certainly surmountable.  But first you've got to decide what  
you
want, then you've got to do the surmounting.

> Just my opinions. Thanks.

No problem!

>   Xah

-- 
Alan Mackenzie (Nuremberg, Germany).

☄

Re: bug#1406: backward-up-list reports scan error incorrectly?

[Xah Lee]

On Nov 27, 4:19 am, Alan Mackenzie <a...@muc.de> wrote:
> Hi, Xah!
>
> > > though, isn't this something easy to fix?
> > No, because it isn't a bug.  It's the way the function is meant to work.
> > If there is a bug, it's that the doc-string (and maybe the elisp manual,
> > I haven't looked) is vague and incomplete.
>
> I've amended the Emacs manual (.../doc/emacs/programs.texi) and the doc
> strings of `backward-up-list' and several similar functions
> (.../lisp/emacs-lisp/lisp.el).
>
> If you're interested, have a look at the changes in
> <http://cvs.savannah.gnu.org/viewvc/emacs/?root=emacs>.

Thanks Alan.

I'd rather hope for a fix instead of change wording to reflect current
situation.

You argued in bug list that the issue is not simple essentially due to
the fact that straight quote chars are not matching.

That is true, but i think given today's tech and computing power, we
should over come this. Just assume that double quotes in the source
code are matched, since they are most of the time. In the few cases
when the backward-up-list went to the wrong place due to un-matched
double quote, i think that's ok.

alternatively, if the cursor is inside double quote, then issue a
warning in the messag area that the result may not be correct.

Also, since this works in text-mode, so another solution is to
temporarily switch to that mode, do the cursor move, then switch back.
Or temp set the syntax table to whatever chat that made text-mode work
and emacs-lisp-mode not work.

In general, my feeling is that moving around nested pairs is a trivial
issue, that given today's technology and software, it seems wimpy to
tell users that backward-up-list won't work if it's inside double
quotes due to some complexities. Much complex problems are solved
today in emacs, in other IDEs, etc.

Thanks though for the fix on the doc.

  Xah
∑ http://xahlee.org/

☄