Calling GPL code from a Python application

[Mike Meyer]

Michel Sanner <sanner at scripps.edu> writes:
> One of the greatest feature of Python in my opinion is the way the
> interpreter can be used to integrate a wide variety of
> software packages by dynamically linking them.  This approach has been
> extremely successful for us so far but now I run
> into a license nightmare.

Which is a good argument against IP in general, but that's another
issue.

> A google search about GPL and dynamic linking came up with an equal
> number of pages saying that dynamic linking of GPL
> code into non GPL applications is allowed as it is the end user who
> cretes the derived work, as pages saying the opposite ! So does anyone
> know what to do about this ?

Yes. Ask the holders of the copyright.

The only way to find out *for sure* whether or not a license allows
something is to do that something, get sued about it, and get a judge
to tell you whether or not you violated the license. Different judges
may well give you different answers.

A critical step in that process is getting sued. The copyright holders
have to do that, so you'll need their cooperation for this. Of course,
if they don't think what you're going to do is a violation of the
license, they may not be willing to sue you, in which case you're out
of luck.

If you want an opinion about whether or not you would win such a
lawsuit, ask a lawyer you trust.

If you want to know the intent of the authors, that is that libraries
covered by the GPL would infect programs they are linked with, whether
it's dynamically or statically. The Library (now Lesser) GPL was
created to to allow programs to be linked with LGPL'ed libraries
without infecting the program. If the library in question was released
under the LGPL, the authors of the GPL say you can use it. Otherwise,
they say not. But see the above paragraphs about judges, copyright
holders and lawyers.

> The second question I would like to get an answer for is whether doing
> an "os.system('GPLapp')" violates GPL if I ship
> my Python code that does the os.system call and the GPLapp program ?

I'm pretty sure that doesn't violate the GPL. But IANAL, so...

    <mike
-- 
Mike Meyer <mwm at mired.org>			http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.