From octave-maintainers-request at bevo dot che dot wisc dot edu Sun Jan  5 21:27:50 2003
Subject: Re: mkpkgadd
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Andy Adler <adler at site dot uottawa dot ca>
Cc: octave-maintainers at bevo dot che dot wisc dot edu
Date: Sun, 5 Jan 2003 21:27:47 -0600

On  5-Jan-2003, Andy Adler <adler at site dot uottawa dot ca> wrote:

| On Sun, 5 Jan 2003, Paul Kienzle wrote:
| > I've started adding PKGADD stuff to octave-forge.
| 
| I'm sorry, I haven't heard about PKGADD before.
| It seems to be a fairly important thing to understand.
| 
| Could anyone refer me to a place where I could learn
| about what PKGADD is and how to deal with it?

This feature is new with the most recent snapshots and current CVS
sources.

Now when Octave adds a directory to the load path, it looks for a file
called PKG_ADD in that directory, and if it exists, reads it and
executes any commands found in it.  Any valid Octave code can go in
these files, so it is like a per-directory octaverc file.

The motivation for adding this feature was to have a place to put
the new "mark_as_command" declaration statements that allow us to mark
M-file functions as commands so they can be called as (for example)

  grid on

instead of

  grid ("on")

Currently, the only things in any PKG_ADD files that are installed
with Octave are a few "mark_as_command" statements, but we may use
these files for more in the future.

There is a script in the CVS archive (I accidentally omitted it from
the latest snapshot files, but it will be in 2.1.44) called mkpkgadd
that is used when installing M-files.  It looks for lines like

  ## PKG_ADD: ... code ...

in M-files and copies the "... code ..." part to the PKG_ADD file that
goes in the directory where the M-files are installed.  You'll have to
look at the Makefiles in the scripts directory to see how it is used.

Also, when a directory removed from the load path, Octave looks for a
file called PKG_DEL in the directory that is being removed, and runs
commands found there.  So far we are not using this feature, but it
could be useful if you want to clean up after a package that has been
removed from the load path (for example, to remove global variables,
or close and clean up temporary files, etc.).

jwe