Python, licenses and CVS

Kragen Sitaker kragen at canonical.org
Mon Nov 26 14:32:39 EST 2001


Hans Nowak <wurmy at earthlink.net> writes:
> I have a follow-up question though. The project I'm currently
> working on is well suited for third-party contributions; it makes
> sense for others to add modules if they want to. If my code is
> released under, say, the GPL, what happens when someone else wants
> to contribute to it? Does the new code have to be GPL too? Or
> GPL-compatible?

Briefly, yes.

The GNU General Public License does not allow other people to
incorporate your program into a program that is licensed more
restrictively.  So if someone writes a module they want to become part
of your program, they must either grant people the right to use, copy,
modify, and redistribute their code under the GNU GPL or get you to
grant a more liberal license to your code.

Other ('non-copyleft') licenses, such as the BSD license, don't impose
this restriction.  As a result, if you license your code under the BSD
license, someone can add some proprietary modification, run py2exe on
it, and sell it under a standard proprietary-software EULA for $500 a
pop: "Purchaser agrees not to decompile, reverse-engineer, or
disassemble the Software."

Some people see this as an advantage of non-GPL licenses like
Python's, which result in the software being used more widely; other
people see this as an advantage of the GPL, which results in all the
users of the software having the freedoms to use, copy, modify, and
redistribute it.




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