During the python-mode project's short life, I've copied python-mode.el over to the Python project's Misc directory a few times. I thought I'd better ask if GPL-ness would present a problem. I have always remained blissfully unaware of licensing details, so I have no grasp of what the ramifications are.

From http://www.gnu.org/licenses/gpl-faq.html#MereAggregation:

Mere aggregation of two programs means putting them side by side on the same CD-ROM or hard disk. We use this term in the case where they are separate programs, not parts of a single program. In this case, if one of the programs is covered by the GPL, it has no effect on the other program. Combining two modules means connecting them together so that they form a single larger program. If either part is covered by the GPL, the whole combination must also be released under the GPL--if you can't, or won't, do that, you may not combine them. What constitutes combining two parts into one program? This is a legal question, which ultimately judges will decide. We believe that a proper criterion depends both on the mechanism of communication (exec, pipes, rpc, function calls within a shared address space, etc.) and the semantics of the communication (what kinds of information are interchanged). If the modules are included in the same executable file, they are definitely combined in one program. If modules are designed to run linked together in a shared address space, that almost surely means combining them into one program. By contrast, pipes, sockets and command-line arguments are communication mechanisms normally used between two separate programs. So when they are used for communication, the modules normally are separate programs. But if the semantics of the communication are intimate enough, exchanging complex internal data structures, that too could be a basis to consider the two parts as combined into a larger program.

Not too long ago, Matthias Klose submitted an enormous patch (1370 lines) to python-mode.el (only 3804 lines itself):

https://sourceforge.net/tracker/index.php?func=detail&aid=875596&group_id=86916&atid=581351

I decided to start disecting it today and immediately ran into this comment by Dave Love (fx@gnu.org):

;; This file contains significant bits of GPL'd code, so it must be ;; under the GPL. -- fx

During the python-mode project's short life, I've copied python-mode.el over to the Python project's Misc directory a few times. I thought I'd better ask if GPL-ness would present a problem. I have always remained blissfully unaware of licensing details, so I have no grasp of what the ramifications are.

Serious. Do not copy this into Python. I would recomment rejecting the patch for python-mode.el as well (isn't that project also using the PSF license?). --Guido van Rossum (home page: http://www.python.org/~guido/)