Docs about block comments, Emacsisms

[John W. Eaton]

On 11-Jan-2011, Jordi Gutiérrez Hermoso wrote:

| but the mailing list seems to have rejected his email with the
| following message:
| 
|      RCPT TO <address@hidden> failed: must be
|      authenticated

I don't know what happened there, but the message was held for
approval.  Since it looked like a problem report, I rejected it with a
note about filing bug reports on the bug tracker, but I kind of
botched that job and hit the send button too early.

| At any rate, he raises a couple of interesting points.
| 
| 1) What is the state of block comments? I see that the FAQ has been
| updated, but only seems to refer to one style of block comments, with
| %{ %} and not with #{ #}. Do they work like they do in Matlab now?

Mostly.  There are still some contexts where block comments do not
work properly, like inside [] and {} when defining literal matrix or
cell array objects.  See the comments in lex.ll.

| 2) What should we do about Emacsisms in the manual? <DEL> is how Emacs
| and GNU documentation refers to the backspace key, but this may be
| obscure to people who aren't familiar with the overall GNU system. As
| far as I can tell, the notation for keybindings isn't explained in the
| Octave manual itself. I only recall this from the Emacs manual.

I think <Delete> and <Backspace> should be distinct.  The problem for
Emacs is apparently that <Backspace> and C-h are the same, and C-h is
used as the help command prefix.

When I run Emacs, <Backspace> is bound to delete-backward-char, which
deletes characters before the point, and <Delete> is bound to
delete-char, which deletes characters after the point.  But when I run
bash or Octave in a shell, both have the same effect.  I'm not sure
why.  I have the gnome-terminal settings:

  Backspace key generates:  ASCII DEL
  Delete key generates:     Escape sequence

and my stty setting for erase is \? (ASCII DEL).

Maybe that's it?  Anyway, this is a complicated mess since there seem
to be so many things that can have an effect on what the key is
actually doing before Octave/readline sees it.  So should we just say
something about how the keybindings depend in part on what Octave
sees, and that these are just the defaults?  I have little desire to
try to include a comprehensive discussion about all the possibilities
in the Octave manual.

jwe