> Part of me wonders if Copy left viral licenses are the only way to combat this. If you are going to use a bunch of critical open source projects in your code base, and you aren't going to pay, you should at least pay it forward by making your source code available.
This is a tough decision, and one that is going to be different for each project.
GPL will disuade most commercial projects from using your library, which for some people may be a good goal in itself. But the flip side of that is that a GPL'd library has a smaller target audience, which means that the project as a whole will tend to never become as popular as OpenCV has*. That's probably good for the maintainer's health—GPL serves as a good gatekeeper to push away a good chunk of the entitled demands (except for the entitled demands to change the license)—but it may be counter to the maintainer's goal if they set out to make a library with wide reach.
* The notable exceptions to this rule, like Linux, aren't libraries, they're applications or operating systems which can be used without paying it forward.
Yeah, like I said, for some projects I could see it being a net positive: using GPL almost certainly increases the ratio of contributors:users, which reduces the burden on the maintainer. If the maintainer is fine with the now-limited reach of the project, then that might be a great tradeoff to make!
This is a tough decision, and one that is going to be different for each project.
GPL will disuade most commercial projects from using your library, which for some people may be a good goal in itself. But the flip side of that is that a GPL'd library has a smaller target audience, which means that the project as a whole will tend to never become as popular as OpenCV has*. That's probably good for the maintainer's health—GPL serves as a good gatekeeper to push away a good chunk of the entitled demands (except for the entitled demands to change the license)—but it may be counter to the maintainer's goal if they set out to make a library with wide reach.
* The notable exceptions to this rule, like Linux, aren't libraries, they're applications or operating systems which can be used without paying it forward.