python and gpl

Scott Robinson dscottr at bellatlantic.net
Mon Jan 31 21:12:29 CET 2005


On 30 Jan 2005 21:59:25 -0800, Paul Rubin
<http://phr.cx@NOSPAM.invalid> wrote:

>John Hunter <jdhunter at ace.bsd.uchicago.edu> writes:
>> The question is: does shipping a backend which imports a module that
>> links with GPL code make some or all of the library GPL.
>
>Literally speaking, no, not automatically, any more than driving a car
>makes you into a licensed driver if you weren't one already.  But if
>you weren't licensed, then you've broken the law by driving the car.
>So your question should be: 1) is shipping that backend one of the
>things you need the GPL to license you to legally do, and 2) if so,
>does the GPL in fact give you that license?
>
>If you're asking in terms of legal enforcement, the answer is 1) maybe
>and 2) almost certainly not.  I think it's better to ask in terms of
>the GPL's spirit.  I would say that it's not in the GPL's spirit and
>that GPL die-hards would consider that use objectionable, though they
>might make exceptions for specific cases (so it doesn't hurt to ask).
>Some authors who use the GPL are less strict about how they interpret
>it, so again, the friendly thing to do is ask the author.
>
>  * If a backend module somebackend does
>
>     import somelib
>
>    where somelib is a python wrapper of GPL code, is somebackend GPLd?
>
>It's GPL'd if you GPL it.  If you don't GPL it, then distributing it
>it may be a GPL violation that could get you taken to court.  I
>believe the FSF's view is that it is fact a violation; however, the
>courts have not yet established this.  The law doesn't have a
>black-and-white boundary.  It's more like a fractal.  The only way to
>find out what a court will decide is to actually try a case there.
>
>Rather than try to probe how closely you can dance around the
>boundaries of the GPL, you might just ask the author of the GPL'd
>library whether what you want to do is ok with him or her.  If s/he
>says no and you do it anyway, you're both inviting trouble over the
>possible infringement, and also inviting people to try to use your
>code in ways you don't like.  Since the free software movement depends
>on a spirit of cooperation, I think it's best to avoid trying to press
>too hard against the boundaries of anyone's licenses.
>
>http://www.gnu.org/licenses/gpl-faq.html

If you read the GPL, it claims everything it can (any "work" created
using GPLed "work").  My guess is that anything that calls the code in
a way not specifically allowed by the author is going to get you into
trouble.  IANAL, but from what I can remember about earlier licensing
issues, any code specific for a GPLed library (especially "import")
will get you into to trouble.  Having a non-free library with an
identical API and issuing 
	exec("import "+sys.argv[1])
where the user can supply sys.argv as the name of the gpl'ed library
will work (I think there is a free/non-free library out there that is
never run, but exists for exactly this condition).

Scott Robinson




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