Writing PNG with pure Python

[Johann C. Rocholl]

> > I have now decided to license my project (including the pure python PNG
> > library) under the Apache License 2.0 which is less restrictive than
> > the GPL in terms of sublicensing.
>
> But it is also incompatible with the GPL:
>
> http://www.fsf.org/licensing/licenses/index_html#GPLIncompatibleLicenses

Thank you for enlightening me. I was under the wrong impression that
the Apache License was compatible with the GPL, perhaps because it is
OSI-approved, which means a different thing as I now understand.

> If you're convinced that a permissive licence suits your code best,
> please consider something whose side-effects you understand. If the
> additional patent grant or licence termination clauses (which the FSF
> don't regard as a bad thing, just something incompatible with the
> current GPL/LGPL) are specifically what you want, then the Apache
> Licence may be what you're after; otherwise, you should choose
> something less baroque and better understood, perhaps from this list:
>
> http://www.fsf.org/licensing/licenses/index_html#GPLCompatibleLicenses

I do believe that my code will be useful for more people if it's under
a permissive license, but obviously also if it's under a GPL-compatible
license. Therefore it's perhaps a good idea to change the license of my
software again.

Currently, I am considering the following options:
- LGPL
- Modified BSD License
- X11 License (aka MIT License)

I appreciate the simplicity of the BSD and MIT Licenses, except for the
names. "BSD License" can be confused with the original BSD License,
while "MIT License" according to the FSF "is misleading, since MIT has
used many licenses for software." But perhaps these drawbacks are just
mentioned on the FSF page to get more people to use the GPL or LGPL.
:-)

I don't want to start a holy war about the benefits of the GPL, but I
would like some more input about the choices of licensing. Perhaps I'll
put the larger part of my Project under the GPL and only some
standalone library parts (like the PNG encoder) under the LGPL.

If I ever want to contribute some of the code to the Python Software
Foundation, I can still license it to them under the Apache License,
right? But how about the parts of the code that others contribute to my
software while it's licensed under the LGPL?

Cheers, Johann