Choosing the right open source license

Question

My goals for the open-source license is credit for contributions like I get credit for the code I write and I would like if a person shows me a concept of how to do something and I implement it I want him to get credit for showing me how I could do something, but he never showed any code, so the code I wrote for it is mine, but the idea/concept was his.

I would also like something where "I give you source code you give me your changes back." (quote from Linus Torvalds https://youtu.be/PaKIZ7gJlRU?t=24 24-45) I was thinking GNU General Public License v2.0 would satisfy these needs but would like more opinions on if this is the right choice.

The code will be written in a game called Garry's mod using the steam workshop add-on called wire mod. Within the add-on is an Expression 2 toll which is where the code is run and can be saved within the game to a txt file which later can be opened or copied from to rerun/run the code. I believe the add-on source code is available on GitHub under Apache 2.0.

Answer 1

I think the GPL will do most of what you ask, though see the two exceptions below. The latest version is GPLv3, so unless you have a specific reason for wanting to use GPLv2, it may be better to stay current.

You desire that someone who shows you an idea, let's call her Alice, should be entitled to a credit. There are problems with embedding that requirement in a copyright licence. Firstly, if the rest of the code is yours, the licence doesn't bind you, so even if you were to write such a licence it wouldn't force you to credit Alice. Secondly, ideas aren't copyrightable, only the expression of them, which you have stipulated that Alice didn't provide. However, it's your code base, so nothing stops you from giving Alice a copyright interest in it. If Alice had given or shown you her ideas in code, and you had then used them in the same or a derivative form, that would give her a copyright interest in the resulting work as a matter of right, and you would need do nothing to further that as long as you and she live in Berne convention signatory countries (which is nearly all of them).

Also, you desire that anyone who makes changes should be required to give them back to you. That is not what the GPL requires; it says that anyone distributing a modified version in binary form must also give the full source code, under GPL, to the recipient(s) of the binary. It is assumed that from there, those contributions will make their way back to the community, and in practice it's generally so; but that's not exactly what you ask for. We discuss elsewhere the idea of forcing modifications to be contributed back to the original author, and it is generally thought of as being a non-free requirement. So you can do this, if you want, but your software will not be usable by substantial sections of the free-software community.