Jython

>  From discussions on the Debian list, there's apparently a 
> GPL-incompatibility in the Jython license, and some Debian was concerned 
> about the inclusion of the Readline stuff (because it links to the GPL'd 
> gnu readline library).

The problem derives from the cpython 2.0 license used with jython.  From
cpython's own license file:

  All Python releases are Open Source (see http://www.opensource.org for
  the Open Source Definition).  Historically, most, but not all, Python
  releases have also been GPL-compatible; the table below summarizes
  the various releases.

      Release         Derived     Year        Owner       GPL-
                      from                                compatible? (1)

      0.9.0 thru 1.2              1991-1995   CWI         yes
      1.3 thru 1.5.2  1.2         1995-1999   CNRI        yes
      1.6             1.5.2       2000        CNRI        no
      2.0             1.6         2000        BeOpen.com  no
      1.6.1           1.6         2001        CNRI        yes (2)
      2.1             2.0+1.6.1   2001        PSF         no
      2.0.1           2.0+1.6.1   2001        PSF         yes
      2.1.1           2.1+2.0.1   2001        PSF         yes
      2.2             2.1.1       2001        PSF         yes
      2.1.2           2.1.1       2002        PSF         yes
      2.1.3           2.1.2       2002        PSF         yes
      2.2.1           2.2         2002        PSF         yes
      2.2.2           2.2.1       2002        PSF         yes
      2.3             2.2.2       2002-2003   PSF         yes

  Footnotes:

  (1) GPL-compatible doesn't mean that we're distributing Python under
      the GPL.  All Python licenses, unlike the GPL, let you distribute
      a modified version without making your changes open source.  The
      GPL-compatible licenses make it possible to combine Python with
      other software that is released under the GPL; the others don't.

  (2) According to Richard Stallman, 1.6.1 is not GPL-compatible,
      because its license has a choice of law clause.  According to
      CNRI, however, Stallman's lawyer has told CNRI's lawyer that 1.6.1
      is "not incompatible" with the GPL.

Debian's solution to the readline problem was to not link against
libreadline but instead libedit which is BSD licensed.  Bernhard Bablok
was happy to take patches to his readline wrappers to ensure this was
possible.

Ben (debian jython maintainer).

Ben Burton wrote:

>> From discussions on the Debian list, there's apparently a 
>>GPL-incompatibility in the Jython license, and some Debian was concerned 
>>about the inclusion of the Readline stuff (because it links to the GPL'd 
>>gnu readline library).
>>    
>>
>
>The problem derives from the cpython 2.0 license used with jython.  From
>cpython's own license file:
>
[snip]
Thanks for the clarification & info, Ben.

However, I wasn't able to find any link/dependency to the CPython 2.0 
license in current Jython.

http://www.jython.org/license.html is the same as the LICENSE.txt file 
included in the Jython distribution, and doesn't cite the CPython 2.0 
license, rather the JPython 1.1 license, which has the (questionable) 
choice of law clause, the (derided) acceptance ceremony, and the (???) 
revocability clause.

Jython distributions do include parts of the appropriate CPython library 
(currently 2.1, moving to 2.2), and so the LICENSE.txt should probably 
cite the appropriate CPython license (with which we comply by retaining 
PSF copyright notices and including brief descriptions of changes to the 
Python library).

>Debian's solution to the readline problem was to not link against
>libreadline but instead libedit which is BSD licensed.  Bernhard Bablok
>was happy to take patches to his readline wrappers to ensure this was
>possible.
>
:-)

kb

> However, I wasn't able to find any link/dependency to the CPython 2.0 
> license in current Jython.
> 
> http://www.jython.org/license.html is the same as the LICENSE.txt file 
> included in the Jython distribution, and doesn't cite the CPython 2.0 
> license, rather the JPython 1.1 license, which has the (questionable) 
> choice of law clause, the (derided) acceptance ceremony, and the (???) 
> revocability clause.

Well okay, call it what you will but AIUI the jpython 1.1 license is
more or less the old CRNI license that was once used with cpython.  I
could be wrong here but regardless of that it would seem to have the same
problems that caused cpython to change their license with python 2.0.1.

The link http://www.python.org/2.1/fsf.html from the cpython site seems
to explain some of these GPL compatibility problems; in particular the
acceptance ceremony and the choice of law clause both seem to be
problematic.

Ben. :)