Stephan Richter wrote:
Anything you build on top of lovely.rating can be ZPL, since
schooltool.requirement is used as a library that is not extended.
I do not understand how "is used as a library that is not extended"
affects matters? Using a GPL-ed component as a library without extending
it doesn't mean I can stop worrying about the GPL when using it in a
larger program, as far as I understand.
What you say is true though: anything built on top of a GPL-ed package
can be ZPL.
There is a 'but' here though, and this has to do with expectations and
the underlying reasons the ZPL is the license of the Zope repository and
people tend to be careful about GPL-ed stuff.
I think the provisions of the GPL state that anything that links to a
GPL-ed component will need to be distributable under the terms of the GPL:
"These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the Program, and
can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works. But when you
distribute the same sections as part of a whole which is a work based on
the Program, the distribution of the whole must be on the terms of this
License, whose permissions for other licensees extend to the entire
whole, and thus to each and every part regardless of who wrote it."
So, in my I'm-not-a-lawyer-thank-goodness reading, that means that if I
distribute software with a GPL-ed component in it, I need to distribute
all the components in this under the provision of the GPL as well. This
additional stuff can indeed be ZPL, but since GPL is in there, I cannot
distribute proprietary code that uses this software stack, unless I rip
out the GPL dependency first. That is, if I give my code to someone, I
must give them the source code of everything involved, and they can give
that source code to anyone they like, under the provisions of the GPL.
The expectation one may have of a ZPL-ed codebase is that it is useable
even in proprietary settings without having to comply to the rules of
the GPL. This is not the case for a ZPL-ed component which relies on a
Whether one considers this right, proper or fair is another debate I do
not want to go into.
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