By the way, what's the copyright status of code copied from cookbooks? A
cookbook is supposed to be a place from where you can quickly and easily
adapt some code to get a job done. So tricky licensing defeats the whole
purpose - if you need to worry about copyright or paste some wordy
license into your project, then it's easier to just go without the
cookbook altogether and do some detective work to come up with your own
code from scratch.
Below some minimal size, I doubt it matters.
If we do end up maintaining the cookbook, we should just make the license clear on every page. Perhaps we could even annotate old code as having only the old license, but include a user agreement that licenses code under multiple licenses so that users have the most flexibility possible. But, of course, I'm not a lawyer in any jurisdiction.
Here's the Stack Overflow licensing policy:
<https://stackoverflow.com/help/licensing>. Apparently they are using
Creative Commons CC-BY-SA for user contributions. For prose it's ok. But
for code snippets - how can it possibly work? Nobody is going to even
realize they should follow that license.
I would trust their approach. They are such a huge site, with so many users, that I assume that they must already have dealt with any possible issue that could come up.
But we should make licensing absolutely clear, perhaps including a tiny "LICENSE" link next to each code snippet.