GPL for Ftwalk

[Tom Hull]

Ftwalk is a script programming language (remotely related to
awk), which I wrote and released as free software several
years ago, using an "artistic" license. I intend to change
the licensing for the next release, to use GPL. All of the
source code refers to "the Ftwalk LICENSE file" for details
on licensing. I'm thinking that rather than change all of
these files to explicitly refer to the GPL, I can just
change "LICENSE" to refer to the GPL. I've also written
some explanation and (I think) clarification in "LICENSE".
I would appreciate any feedback from you regarding this
general approach and/or the specifics of the wording.

Looking ahead, I think the following future steps are
likely:

 1) I would like to start integrating other (primarily
    GPL) open source software, including extensions and
    interfaces to other packages.

 2) Some parts of Ftwalk are currently organized in
    libraries, and others may be reorganized into
    libraries, in which case I may want to license
    those parts using LGPL. (I understand that the
    choice of LGPL or GPL for libraries is a matter
    of tactics, not subject matter.)

The text to my "LICENSE" file follows:

-----------------------------------------------------------------
                            Ftwalk LICENSE

The main body of work in the Ftwalk package is Copyright Tom Hull. The
files that comprise that work refer to the "Ftwalk LICENSE file." This
is the referred-to "Ftwalk LICENSE file". Other files may refer to other
licenses, and may be used, copied, redistributed, and/or modified only
according to the terms specified in those licenses. In most cases such
files are licensed under the terms of the GNU General Public License,
so their licensing terms are equivalent to the main body of work in the
Ftwalk package.

This work is free software. You can redistribute it and/or modify it
under the terms of Version 2 (or any subsequent version) of the GNU
General Public License, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License in
the Ftwalk package, in the file "COPYING"; if not, write to the Free
Software Foundation, Inc., 675 Massachusetts Ave., Cambridge, MA
02139, USA.

Earlier Ftwalk versions (1.5.1 and previous) had been licensed using
an ARTISTIC license. You may, of course, continue to use version
1.5.1 under its ARTISTIC license. However, starting with Ftwalk
1.5.2, Ftwalk is licensed under the GNU General Public License.
If you have a problem with that, please contact Tom Hull.

(The ARTISTIC license is only included with this package for
historical reference, and will be removed at a future date.)

I believe that the practical differences between the old and new
Ftwalk licenses are not significant. The only problem that I am
aware of is that some people (primarily developers of non-free,
non-open source software) believe that the GPL requires them to
offer their non-derived, proprietary software under the GPL if
it is aggregated with GPL-licensed software. As regards Ftwalk,
my interpretation of the GPL is that users who write the following
types of code are not required to release that code under the GPL
(although they may, of course, explicitly choose to do so):

 -- Ftwalk scripts.

 -- New commands that are accessed through the DSO interface.

 -- New commands that are merely linked into Ftwalk package
    executable programs. (It is possible to add new commands
    to Ftwalk without modifying any existing source code.
    This feature makes the addition of compiled, linked-in
    commands equivalent to implementing those commands
    externally.)

In each of these cases, Ftwalk itself is not being modified, so
the redistribution of an unchanged Ftwalk with such proprietary
scripts and/or subroutines is mere aggregation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for details.

-----------------------------------------------------------------
/*
 * Tom Hull
 * thull at home.com | http://www.ocston.org/~thull/ftwalk/
 * thull at sco.com
 */