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Re: Python library under permissive GPL-compatible license optionally using GPL library

On 12/12/2014 11:44 PM, Ángel González wrote:
> Yaroslav Halchenko wrote:
>> Dear fellas who know much more about licensing than me.
>> I might have even asked before (since we are in a similar situation with
>> PyMVPA/shogun) but forgot what was the summary:
>> If we have a library X in Python, released under some GPL-compatible
>> license (e.g. BSD-3 or Expat) and then using (optionally) some GPL code
>> (at run time) provided by another library Y -- what are the implications?
>> Am I wrong on any of the following statements
>> - the project X codebase doesn't have to be relicensed to GPL
>> - the project X can use project Y (since under GPL compatible license)
>> - It is only at 'run time' when actual linking to the library Y happens,
>>    so project must comply with GPL but whose responsibility it is then
>>    and what needs to be enforced?
>>    - original distributor of X must have provided all the sources with
>>      modifications?  But it was user's decision to use GPL'ed library
>>    - or user must somehow make sure he has the sources... (sounds
>>      dubious)
>> - is mere ability to be used with GPL licensed library Y makes
>>    distributors of code of X required to comply with GPL? (e.g. provide
>>    modified sources)
>> Thanks in advance for your feedback
>> [1] http://mail.scipy.org/pipermail/nipy-devel/2014-December/010707.html
> If the distributor were a distro like Debian IMHO:
> - package X can be licensed under Expat
> - package Y is licensed under GPL (I would probably add a warning on
the description)
> As package X already meets GPL requeriments that's not really a problem.
> However, let's call X' to X + GPL-incompatible changes.
> Then X' and Y couldn't be used together.

>From what I've read (and recall), if both X and Y are  independent of
each other (X can function without Y, and Y can be used without X), then
it is okay for X to be GPL-incompatible -- thus allowing one to develop
GPL plug-ins to closed-source programs.

However, it appears that the FSF has updated their stance on this
issue[1]. You cane substitute "GPL-incompatible" for "non-free" without
changing the result, I believe.

Of course, Debian differs from FSF on many points, but this supports
what Ángel has said.


Jonathan Paugh

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