Licenses...

M.-A. Lemburg mal at lemburg.com
Mon Aug 9 11:11:30 CEST 1999


phil wrote:
> 
> On Sun, 08 Aug 99 12:31:22 GMT, philh at vision25.demon.co.uk (Phil Hunt)
> wrote:
> 
> >In article <37AA804D.9A1317C0 at houbits.com> nhead at houbits.com "Nigel Head" writes:
> >> There's no licence statement in the distribution at all for now --
> >> my intention is that anyone can use the contents anyway they want,
> >> for non-commercial purposes, providing they keep a reference to the
> >> original source. Oh yes, and I can't take any responsibility for errors.
> >>
> >> Perhaps one of you experienced people can offer some quick advice as to what I
> >> need to do -- do I need to just add a licence.txt file or must I add a header
> >> to every file? What standard text can I use? Is my intent compatible with the
> >> GPL?
> This post raised some concerns for me since i have a Python extension
> that i was going to add to our latest product release. The product is
> not written in Python, nor does it require Python to be running and
> the extension is there because i thought it was cool. However, i have
> to ask whether it is legal to retain this functionality.

Python itself ships with a BSD style license, which means that
you can use it commercially or non-commercially without having
to pay a fee, but instead including a quote of the license in
your products documentation. You are not obliged to include the
source of your extension or Python program when distributing
them just because they happen to use Python.

> >No. The GPL allows anyone to use the software, for commercial or
> >non-commercial purposes. However, if they distribute the software,
> >they must include all source code, including all source code they
> >write which is linked to the software.
> >
> I don't understand this. What is "the software"? As far as i can tell,
> if the software is distributed in binary format (say as a DLL on
> Windoze boxes) then it can be distributed freely with no conditions.
> I've written an extension to a vehicle tracking product that we
> produce that offers a scripting interface. I'm not sure if anyone will
> use this, but i certainly can't distribute it if i have to distribute
> the Python source. Added to which, i don't want to distribute my
> source (except to selected folk) as i don't need the support grief.

If you link against a GPLed product (even if it's done dynamically!),
the whole construction (your product + the GPLed one) automatically
fall under the GPL. This means that you can still sell and distribute
your product, but only if you include the full source code of
the GPLed product
*plus* your product.

The LGPL is a little different: it allows you to link against the
LGPLed product without the need to ship your source code. You still
have to include the source code of the LGPLed product you're linking
against though (including any changes that you have made to it).

If you are using Python extensions written by different authors,
be sure to check their license statement. In case you have any
doubts get in touch with them before using their code. Most 
extensions are under very similar licenses as Python itself,
but some a GPLed and other LGPLed. Also, some are not valid for
commercial use meaning that you'll have to negotiate a special
license with the author to be able to use in your code. This
usually involves paying a license fee.

Hope this clarifies things a little. More infos on GPL and LGPL
should be available on www.gnu.org. If you are still unsure what
is legal and was is not, go on the safe side and contact your
lawyer to get things straight.

-- 
Marc-Andre Lemburg
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