[PD] Legality of plugins (was Re: Percolate)

[Chris McCormick]

On Fri, Mar 09, 2007 at 12:16:28AM +0100, Thomas Grill wrote:
> Am 09.03.2007 um 00:03 schrieb Tim Blechmann:
> >On Thu, 2007-03-08 at 23:37 +0100, Thomas Grill wrote:
> >>To my mind, flext-based Max externals would only violate the GPL, if
> >>they were shipped closed-source with Max.
> >>If the are GPL'd as well and installed by the user, i don't see  
> >>why this
> >>should be a problem.
> >
> >although i don't really like this clause, the following description is
> >quite clear:
> >http://www.gnu.org/licenses/gpl-faq.html#GPLPluginsInNF
> 
> I knew about this one, but i don't think that this is applicable if  
> there is no actual distribution of the non-GPLd program with GPLd  
> plugins.

Even if you are not distributing them together, when the user combines
them they are doing something that is illegal with respect to the GPL.
It's the same with running binary kernel modules with the Linux Kernel.
Lots of people think it's ok, but it's technically illegal.

GPL v3 I think has better ways of allowing this. If your plugins are
licensed "GPL v2 or later" then they will be able to take advantage of
that. In any case, you have copyright of the software and hence you
can change the license any time you wish, even to a commercial one
(but somebody could fork the old GPL one).

> I might be wrong, though. Anyway, i don't care much - if the GPL is  
> odd enough to violate against such usage i would consider a different  
> license. Idealism gone.

"However, you can resolve that legal problem by adding an exception to
your plug-in's license, giving permission to link it with the non-free
main program."
-- http://www.gnu.org/licenses/gpl-faq.html#GPLPluginsInNF

Or you can use the LGPL which lets you link with non-free software,
but still requires that if people modify your plugin code itself they
must re-distribute their changes under the LGPL. This seems to be the
best option for what you want to do (if you are still concerned with
your users' freedom).

Best,

Chris.

-------------------
chris at mccormick.cx
http://mccormick.cx