Urgent Question about Python licensing

Tim Churches tchur at optushome.com.au
Sat Mar 10 22:24:11 CET 2001

Thomas Wouters wrote:
> On Sat, Mar 10, 2001 at 08:43:26AM +0000, Dave LeBlanc wrote:
> > Hi;
> > While reading up on the recent Python conference on O'Reilly's site
> > (http://python.oreilly.com/news/pythonday1_0301.html - actually on the
> > 'day 2' page), I cam across the following:
> [ The python licence hassles.]
> > My questions are these:
> > 1. What prevents Python and GPL code from being distributed together?
> > If I write some Python code that drives a GPL'd app (but  which does
> > not depend on that app), what prevents me from offering both my python
> > code and the GPL'd app on the same medium (disk/CD/web)?
> 'derives' is a bit of a general and weird term. If your code does not depend
> on a GPL library or binary, you can just distribute it. You can also
> distribute both a GPL application and a Python-licenced application on the
> same medium -- there is no restriction to that, as long as you make clear
> what licence applies to what part. What you cannot do is link a
> Python-licenced piece of software to a GPL-licenced part, *and* distribute
> that resulting binary. Not even using dynamic linking, for some reason.
> (Don't ask me, I'm not a lawyer.) I am not sure if you can attempt to import
> a module, which might be a C module that is covered, possibly indirectly, by
> the GPL. My gut says that that should be just fine, but my gut usually tries
> to empty itself when it comes to lawyerese.

You had me worried there about the implications of all of the above for
the (really exciting, from my point of view) work being done by Duncan
Temple Lang under the aegis of the OmegaHat project (see
http://www.omegahat.org) to make the R statistical environment (see
http://www.r-project.org), which can be built as a shared library,
callable from within Python, and v-v (see
http://www.omegahat.org/RSPython/index.html)? R is GPLed and only GPLed. 

However, the eleventh section (i.e. section number 10 - clearly the GPL
and Python are fellow-travellers) of the GPL (see
http://www.gnu.org/copyleft/gpl.html) states that if you want to
incorporate GPLed software in non-GPLed software (and presumably v-v),
one merely has to ask permission in writing from the authors (or should
that be copyright holders?) of the GPLed software. So there would not
appear to be any absolute impediment to linking Python (as currently
licensed) with GPLed software - you just have to ask permission first. 

Tim Churches

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