Re: Lua licensing thoughts

[David Given <dg@...>]

Polarina wrote:
> Lua bytecode is just data, and GPL doesn't restrict what data a computer
> program uses. Your statement is like saying that you can't view websites
> containing CC licensed art because the browser is GPL licensed.

While the GPL doesn't restrict what data a program *uses*, it *does*
restrict your ability to redistribute that data. Lua bytecode is code
--- it's a compiled program. Therefore, if the source that made it is
GPLd, and you're not the original author, then you must provide a means
to get the source if you want to redistribute it.

On Sun, 2008-09-28 at 17:43 -0500, Rob Hoelz wrote:
> So if all the story is scripted in Lua, and it's under a CC license, I
> can't run it on a GPL engine?

You can *run* it on anything. But you won't be able to *distribute* a
combined package containing the engine and the story, because the two
different licenses are incompatible.

(There's nothing to stop you distributing the story and the engine as
different packages, each with their own license; this is how scummvm
works, which is a GPLd engine which runs proprietary data.)

...

The Oversimplified Guide To Distribution Licensing:

- all pieces of work have an owner.

- the owner can give you the work at their own discretion.

- you may only pass on a piece of work if the owner says you can. If the
owner doesn't say anything, you cannot pass it on.

- the owner may set some rules which dictate the terms in which you can
pass on the work. (This is the license.) If you can't meet the terms,
you can't pass it on.

And that's pretty much it --- all software licensing are variations (and
extensions) of the above. If you look at a few, they all contain big
chunks of boilerplate that repeat the clauses above, in legal language.
It's the rules that allow distribution that are interesting.

For commercial licenses you simply can't redistribute them.

For the MIT license, you may redistribute if: you don't change the
license of the stuff we wrote.

For the GPL license, you may redistribute if: you don't change license
of the stuff we wrote, any modifications you make must also be
distributable under the GPL, you must allow modifications to the stuff
you wrote, and if you distribute binaries you must make source code
available.

For the CC-ND license, you may redistribute if: you don't change the
license of the stuff we wrote, but you can't make modifications.

The GPL and MIT licenses are compatible because the MIT license's rules
are a subset of the GPL's. But complying with the GPL license's rules,
you're simultaneous complying with the MIT's.

But the GPL and the CC-ND license aren't compatible because the GPL
requires you to allow modifications, and the CC-ND disallows
modifications. You cannot simultaneously comply with both licenses, so
you can't distribute a combined package containing work under both licenses.

(The CC-NC part is a usage license, aka an EULA, and they're a totally
different kettle of fish.)

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