Licensing of wrappers around C/C++ code under more restrictive licensing.

Mike C. Fletcher mcfletch at
Mon Mar 1 10:37:50 CET 2004

Graham Dumpleton wrote:

> On 29/02/2004, at 4:09 PM, Mike C. Fletcher wrote:
>> Graham Dumpleton wrote:
>> ...
>> If I understand correctly, the QPL is basically a dual license 
>> encouraging you to either pay Trolltech or GPL your software.
> I presume you actually meant to say "QPL" and not "GPL" in this sentence.

I had, actually, meant GPL, referring to the effect, rather than the 
particular license, though it turns out I'd misunderstood the non-viral 
nature of the QPL.

> Anyway, have been looking at the QPL again, and as far as I can see, it
> doesn't force you to make any code you write which links with the QPL'd
> library available explicitly under the QPL. What it says is:
> 6. You may develop application programs, reusable components and other 
> software items that link with the original or modified versions of the 
> Software. These items, when distributed, are subject to the following 
> requirements:

True, it doesn't appear to require QPL licensing of linked works, only 
"Open Sourcing" of the works.

> Thus, as far as I can tell, it would be quite okay to make the Python
> wrappers themselves available under a BSD/MIT type license as opposed
> to the QPL license.

Looks that way.

> 3. You may make modifications to the Software and distribute your 
> modifications, in a form that is separate from the Software, such as 
> patches.
> That is, need to be able to say that the original package must always
> be redistributed as is, ie., in the form provided, with any changes
> being in a distinct package, such as a patch. I believe this should
> also prevent a free for all as far as people taking/stealing just bits
> of the package and reusing it in other things, but then in practice
> that is almost impossible to enforce. :-(

Sure, a patch that deletes 99% of the original (leaving just copyright 
notices) is pretty easy to create...

> If one had a LGPLish variant of the QPL which doesn't transfer
> conditions on linking, problem may be solved. I don't however now
> of any Open Source license which does that. Does anyone else?

Not me.  I stick to BSD licenses as much as is practical.  Makes 
everything simpler :) . That said, and modulo the annoyance of having 
another license to have to read, dropping the 6a and 6b clauses (on the 
advice of a lawyer, not me ;) ) would seem to have the desired effect 
(no effect on linked code, other than requiring that they be willing to 
give the changes back to you).  You'd likely want to stipulate "in 
source-code form", though.

Anyway, far too much time on this thread tonight.  Have fun,

  Mike C. Fletcher
  Designer, VR Plumber, Coder

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