[Zope-dev] ZPL and GPL licensing issues

[Oliver Bleutgen]

>> as i said before, writing gpl code subclassing zope is a non-sense. even
>> the author cannot, imho, redistribute its work with a plain gpl attached
>> to it. the gpl says that if you link with gpl code *all* the code should
>> be gpl or gpl-compatible (major os components like clibs, compilers, etc
>> are an exception). so even the author cannot do that without licensing
>> under gpl plus some exception ("as a special exception you're allowed to
>> link this code with zope or any other zope product distributed under the
>> zpl".) see the (in)famous gpl vs. qt thread in the debian mailing lists
>> for an in-depth analisys of this problem.


> To me this is the key point. If you GPL license a product (or other
> software) for Zope, you cannot subclass ZPL coded classes in your
> product without violating the GPL. This makes a strict GPL license
> nearly useless for Zope development and incompatible (license-wise) with
> Zope itself. What bugs me is when people point to the ZPL being the
> "problem", it is the GPL that is the limiting factor IMEHO.
> --
> | Casey Duncan
> | Kaivo, Inc.
> | cduncan@kaivo.com
> `------------------>

Either this is wrong, or I don't get it. 

The GPL talks just about _distribution_ of a product,
or more precisely, about the rights of _others_
for distribution.
I can distribute my products with any license I want,
who should have a problem with that and what license
may be violated?
To cite the GPL:
"You must cause any work that you distribute or publish, 
that in whole or in part contains or is derived from 
the Program or any part thereof, to be licensed as a 
whole at no charge to all third parties under the 
terms of this License."

and

"Thus, it is not the intent of this section to claim 
rights or contest your rights to work written entirely by you; 
rather, the intent is to exercise the right to control 
the distribution of derivative or collective works 
based on the Program. "

and (from the GPL-FAQ):

"Is the developer of a GPL-covered program bound by the GPL? 
Could the developer's actions ever be a violation of the GPL?

Strictly speaking, the GPL is a license from the developer for 
others to use, distribute and change the program. 
The developer itself is not bound by it, 
so no matter what the developer does, 
this is not a "violation" of the GPL. 
However, if the developer does something that would violate the 
GPL if done by someone else, the developer will surely 
lose moral standing in the community. "

I.e. I also can publish internet explorer specific
javascript under the gpl (or vb-macros for that 
matter).

and (also from the GPL-FAQ)

"I'm writing a Windows application with Microsoft Visual C++ 
and I will be releasing it under the GPL. Is dynamically 
linking my program with the Visual C++ run-time library 
permitted under the GPL?

Yes, because that run-time library normally accompanies 
the compiler you are using."


The only problem I see is when someone (DC) wants
to incorporate someone else's GPLed product 
together with zope, or when someone wants to modify 
someone elses GPLed zope product and distribute it.

But I think even the second part isn't a problem,
because the GPL says (under section 2, the "viral"
part):

"These requirements apply to the modified work as a whole. 
If identifiable sections of that work are not derived from the 
Program, and can be reasonably considered independent and 
separate works in themselves, then this License, and its 
terms, do not apply to those sections when you distribute 
them as separate works. But when you distribute the same 
sections as part of a whole which is a work based on the Program, 
the distribution of the whole must be on the terms of this License, 
whose permissions for other licensees extend to the entire whole, 
and thus to each and every part regardless of who wrote it. "

For me that means that as long as I distribute someone elses
GPL'ed zope product without zope, it's ok. I guess that we
all are in agreement that zope "can be reasonably considered
independent and separate work in themselves".


cheers,
oliver