Re: Info bug with @xref{Sample .emacs File, , , ccmode, the CC Mode Manual}.

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 11 Dec 2005 21:28:43 +0000 (GMT)
> From: Alan Mackenzie <acm@muc.de>
> cc: emacs-devel@gnu.org
> 
> >   * Unfortunately, you cannot use periods, commas, colons or
> >     parentheses within a node name; these confuse the Texinfo
> >     processors.  Perhaps this limitation will be removed some day, too.
> >
> >So there you are: don't do that ;-)
> 
> Hey, that's not fair!

Who said life's fair? where's that written? ;-)

> We've had a node called "Sample .emacs File" in
> the CC Mode manual since 22nd February 1995, and that was before I could
> even spell "Emacs".  ;-(
> 
> And, so far as I know, we've _NEVER_ had any problems with it.  It has
> simply worked.

Worked with what Info reader?  Different readers have different code
to extract a node name from cross-references and menu lines, so each
one of them will react differently.  I think the standalone reader
(the one distributed with Texinfo) had grave problems with such nodes
several versions ago.  The Emacs's Info reader has changed
considerably between v21.x and now.  If you really wish to dig into
this, you will probably find that one of these changes is responsible
for the breakage.

But the fact remains that node names cannot have periods.

> More to the point, makeinfo has never given a warning about it.

That could be worth reporting to the Texinfo mailing list.  I CC'ed
Karl berry, who maintains Texinfo.

> By the way, WHY can't we have periods in node names?  OK, we need commas
> to separate the arguments of the @xref and info node, we need colons to
> delimit the node name, we need parens to give an info filename.  But why
> periods?

Because in the produced Info manual, the period is also one of the
delimiters of the node name in menu items and cross-references.
Consider this:

  *Note Foo: Bar.

Here `Bar' is the name of a node, and it is delimited by the colon and
the period.  `Foo' is what was in the second argument of the @xref
directive.

> Over ten years of "@node Sample .emacs File" suggests that the
> restriction isn't really necessary.

I think it is necessary; you've just been lucky: you never used a
cross-reference with its second argument non-empty.  When the second
argument is empty, the node name is delimited by "::", which, in the
Emacs Info reader, is enough to extract the node name.