On 11/11/10 01:32 PM, Jason Grout wrote:
As I understand it, currently, the whole Sage distribution is
effectively GPLv3+, since it combines GPLv2+ and GPLv3+ code, so it is
at least GPLv3. My understanding is that we currently can't include GPL2
(not +) code. However, if someone wanted to take just the Sage library
and certain GPLv2+ packages (something like Purple Sage), then they
could make a GPLv2+ distribution, and then they could incorporate GPLv2
(not +) code into their distribution.
Another resource for this is the GPL FAQ, particularly:
http://www.gnu.org/licenses/gpl-faq.html#AllCompatibility
Thanks,
Jason
Thank you Jason. The particular page I was updating is just about adding new
.spkg files and not the library, so we don't need to address that here. I think
that's simpler anyway, but that's not the issue.
One problem is that 95% of people don't actually follow the instructions in the
GPL, but simply copy the 'COPYING' file, so it ends with:
<signature of Ty Coon>, 1 April 1989
Ty Coon, President of Vice
That also means 95% of people don't actually add "or any later version" to their
GPL2 code. For example, Maxima says:
GNU GENERAL PUBLIC LICENSE
Version 2, June 1991
with no mention the code can be used under any later version of the GPL. If you
look at the nset.lisp, it says
; Released under terms of GNU GPL v2 with Bill's approval.
with no mention whatsoever of the "or later".
http://www.gnu.org/licenses/gpl-faq.html#AllCompatibility
is interesting. I must admit, reading that, I don't think there's a single
license Sage can claim to conform to!
For example, if we want to release code under "GPLv2 or later", which is what
the Developers Guide currently says Sage is, then looking at that matrix, if we
want to included GPL3 code, it says:
"OK if you upgrade to GPLv3 [3]"
Reading note number 3, it says
"3: If you have the ability to release the project under GPLv2 or any later
version, you can choose to release it under GPLv3 or any later version—and once
you do that, you'll be able to incorporate the code released under GPLv3."
This is a huge can of worms, it really is. I think the FSF made a real f***-up
in releasing GPL v3.
I really see no sensible way that this section of the developers guide.
I think given my intension was to update the section about supported platforms,
I will leave untouched this bit about licensing.
Dave
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