[DB-SIG] Re: [Psycopg] GPL or LGPL

M.-A. Lemburg mal@lemburg.com
Wed, 02 Oct 2002 10:25:16 +0200

Federico Di Gregorio wrote:
> Il mer, 2002-10-02 alle 00:04, Tom Jenkins ha scritto:
>>I have read these and I don't believe the GPL fits the stated goal of 
>> From why-not-lgpl
>>"The GNU Project has two principal licenses to use for libraries. One is 
>>the GNU Library GPL; the other is the ordinary GNU GPL. The choice of 
>>license makes a big difference: using the Library GPL permits use of the 
>>library in proprietary programs; using the ordinary GPL for a library 
>>makes it available only for free programs.
> let's restate the problem: bash is GPL'ed. should *any* sh script be
> released under the GPL? 

bash happens to be part of the OS, so it triggers the special
LGPL like clause in the GPL which excludes software using
OS facilities from the GPL restrictions.

> or only the ones using bash extensions to
> standard bourne shell? and why is python (and its extension psycopg)
> diferent from a shell?
> the only problem i can forsee is people mixing GPL'ed and proprietary
> modules written in C in the same python, but still then, they are
> independently linking with python (unless the proprietary module call
> the GPL'ed one).

Please see my other reply. It doesn't matter which method of
"combining" the GPLed work and your work is chosen. The GPL
always applies to the work as a whole.

Now, back to the topic:

A Python database extension released
under the GPL will only be usable in applications under the terms
and conditions of the GPL, i.e. if you want to distribute the
application to third parties, you have to ship it with complete
source code.

Note that this can be used (and is used) as business model:
if a customer wants to build a closed source application
around the GPLed database module, the customer would have
to license the database module from the author under different
licensing terms. Of course, this only works if you can
identify the copyright holder -- depending on how the GPLed
project is managed, this can be difficult.

OTOH, if the idea is not to use the GPL as business model,
you might as well switch to the LGPL and thereby reach out to
a larger user base.

Marc-Andre Lemburg
CEO eGenix.com Software GmbH
eGenix.com -- Makers of the Python mx Extensions: mxDateTime,mxODBC,...
Python Consulting:                               http://www.egenix.com/
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