Compulsory checkin clauses.

[John Cowan]

On Sat, 5 Aug 2000, Justin Wells wrote:

> How about releasing a modification to a GPL'd program which contains no 
> material from the original? Recipients of the modification can "privately"
> apply it to their GPL'd works, while the authors of the modification can 
> claim that it is not covered by the GPL because it is not a derived work.

I brought up this point last year (I think) under the title "How to break
the GPL".  The trouble is, according to some of the lawyers on this list,
that establishing copyright in a patch is very unlikely, since there
tends to be a form/content merger (if there is basically only one way to
express something, the form in which it is expressed cannot be copyrighted,
at least in the U.S., as that would create rights over the content as well).
So a proprietary patch to a free program probably won't fly.

> For example, a GPL'd program contains a file called 'foo.c' among its 
> source code. I write a brand new 'foo.c' containing no material from the
> original, but compatibly conforming to its API, and release that under
> some proprietary license. I include a build script which copies my foo.c
> over top of the original and conveniently builds the modified version for
> the people who purchased my foo.c from me.

This is a stronger case, because "foo" is a genuine module with an
exposed API.  (Of course, you have to have read only the API documentation,
not "foo.c", to have any hope of being clean-room.)  If a module]
has a released API, I don't see that there's any hope of preventing
people from replacing it by another module.

Anyway, is that really so bad?  Is there some reason why Random Users, Inc.
*must* link their GPLed programs against either the operating system libc
or glibc?  Why should RUI be forbidden to link the program with
Fred Foobar's Very Fast Proprietary Assembly Language Version Of strstr(),
which just happens to be called in the inner loop of your GPL program?
RUI benefits from paying Fred Foobar, but nobody else is *injured* by this,
unless RUI distributes their binary, which they cannot do under the GPL.

-- 
John Cowan                                   cowan at ccil.org
C'est la` pourtant que se livre le sens du dire, de ce que, s'y conjuguant
le nyania qui bruit des sexes en compagnie, il supplee a ce qu'entre eux,
de rapport nyait pas.               -- Jacques Lacan, "L'Etourdit"