bug#20815: 25.0.50; doc of `null'

bug#20815: 25.0.50; doc of `null'

[Drew Adams]

The doc string should make clear that this is a Boolean
predicate.  Currently it says only "Return t if OBJECT is
nil.  It should also say "Return nil if OBJECT is non-nil.

The Elisp manual (node `List-related Predicates' (which should
be written `List-Related Predicates') is OK.  It says what the
return value is if OBJECT is not nil.



In GNU Emacs 25.0.50.1 (i686-pc-mingw32)
 of 2014-10-20 on LEG570
Bzr revision: 118168 rgm@gnu.org-20141020195941-icp42t8ttcnud09g
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --enable-checking=yes,glyphs CPPFLAGS=-DGLYPH_DEBUG=1'

bug#20815: 25.0.50; doc of `null'

[Drew Adams]

BTW, the URL for the online manual is not good for this node.

Following the convention, it should be simply
http://www.gnu.org/software/emacs/manual/html_node/elisp/List-related-Predicates.html

But it is instead:
http://www.gnu.org/software/emacs/manual/html_node/elisp/List_002drelated-Predicates.html

Somehow, the hyphen got translated to `_002d', unhelpfully.

It is good to follow a consistent convention.  I take advantage
of that, for example, in this command, which I use several times
a day to point Web readers to the manual (e.g. from stackoverflow
and emacs.stackexchange.com):

(defun Info-goto-node-web (node &optional flip-new-win)
  "Use `browse-url' to go to Info node NODE using a Web browser.
With a prefix arg, reverse the effect of option
option`browse-url-new-window-flag'.

NODE is the name of a node in the GNU Emacs or Elisp manual.
Alternatively, NODE can have the form (MANUAL)NODE, where MANUAL is
\"emacs\" or \"elisp\" and NODE is the name of the node in that
manual.  Empty NODE in (MANUAL) defaults to the `Top' node."
  (interactive
   (list (Info-read-node-name "Go to node: " Info-current-node)
         current-prefix-arg))
  (require 'browse-url)
  (unless Info-current-file (error "This command must be invoked from Info"))
  (browse-url (Info-url-for-node node)
              (list (if flip-new-win
                        (not browse-url-new-window-flag)
                      browse-url-new-window-flag))))

`Info-url-for-node' returns "a URL for NODE, a node in the GNU
Emacs or Elisp manual."  It does this:
(replace-regexp-in-string "[ \t]+" "-" node t t).  That doesn't
DTRT for the node reported in this bug report, for example.

bug#20815: 25.0.50; doc of `null'

[Eli Zaretskii]

> Date: Sun, 14 Jun 2015 15:31:46 -0700 (PDT)
> From: Drew Adams <drew.adams@oracle.com>
> 
> BTW, the URL for the online manual is not good for this node.
> 
> Following the convention, it should be simply
> http://www.gnu.org/software/emacs/manual/html_node/elisp/List-related-Predicates.html
> 
> But it is instead:
> http://www.gnu.org/software/emacs/manual/html_node/elisp/List_002drelated-Predicates.html
> 
> Somehow, the hyphen got translated to `_002d', unhelpfully.

Hex 2d is the codepoint of the hyphen.  Makeinfo converts all
punctuation characters like that, so the only hyphens left in the
node's name are those that were spaces before.

IOW, it's a feature.

bug#20815: 25.0.50; doc of `null'

[Nicolas Petton]

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

> The doc string should make clear that this is a Boolean
> predicate.  Currently it says only "Return t if OBJECT is
> nil.  It should also say "Return nil if OBJECT is non-nil.

I pushed a fix (commit deb6e89).

Nico
-- 
Nicolas Petton
http://nicolas-petton.fr

bug#20815: 25.0.50; doc of `null'

[Drew Adams]

> > Somehow, the hyphen got translated to `_002d', unhelpfully.
> 
> Hex 2d is the codepoint of the hyphen.  Makeinfo converts all
> punctuation characters like that, so the only hyphens left in the
> node's name are those that were spaces before.
> 
> IOW, it's a feature.

Too bad, but OK.  It's unrelated to this bug, anyway.