Writing PNG with pure Python

Ben Finney bignose+hates-spam at benfinney.id.au
Tue Jun 13 07:22:21 CEST 2006

"Johann C. Rocholl" <jcrocholl at googlemail.com> writes:

> 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 think these are real concerns. Discussion of these licenses usually
needs to be couched in clarifications, such as "the three-clause
BSD-style license" or "the MIT X11 license"; but these clarifications
are also often dropped, leaving ambiguity as to exactly which license
terms are being discussed.

If you want a permissive, GPL-compatible, copyright-preserving
license, the Expat license is probably the simplest.


> 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.

The FSF licensing webpage offers assistance via email in choosing a


> 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?

This would be a reason to choose something like the Expat license; it
isn't a copyleft, so others can take your code and redistribute it
under a *different* license, such as the Apache license, without
seeking extra permission from you.

> But how about the parts of the code that others contribute to my
> software while it's licensed under the LGPL?

You could require that all contributions be licensed by the author
under the Expat license, allowing you to take it into the whole
without needing to seek out that author in future, while still
preserving their copyright.

 \            "I was in the grocery store. I saw a sign that said 'pet |
  `\      supplies'. So I did. Then I went outside and saw a sign that |
_o__)                          said 'compact cars'."  -- Steven Wright |
Ben Finney

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