I offer the following as solely my own opinion, which has no legal authority of any sort.
1. When creating a derivative work, you should always credit the authors of the portion of your work which you did not create. It doesn’t matter if the authors are reachable or not. It’s their work, not yours. Give them credit, it’s the right thing to do. And it is part of the GPL terms which allow you to use their work in the first place.
As part of the GPL terms, that portion which you did not create must continue to be distributed under GPL, meaning the source code must be available and others may freely distribute and use and modify it under the same terms.
2. You should rename it. It is a derivative work, not an extension of the same work. You should not extend a work without express permission.
3. I don’t know, but I’m sure other plugins in the repository use portions of GPL code of others, so I don’t see a problem with derivative work, only extension of the same work.
4. The original work must always be credited, regardless of how many levels of derivative works are created using it. It is part of the terms of the GPL that allowed you to use the work in the first place.
I make a clear distinction of extending a work versus a derivative work. A simple “take over”, where you simply maintain the code without adding any new functionality is an extension of the same work and not allowed without express permission. A derivative work where you add unique functionality, making it a different product worthy of a different name, is always permissible if the original code is maintained in accordance with the GPL under which it was distributed. You do not need permission to create a derivative work, but under GPL terms, you must credit the original work.
Thank you for that generous descriptive answer. It really does help me in understanding differences between extending an existing code and deriving new code from it.
Today I actually came across SEO Smart Links whilst searching for an autolinks (autolinking of posts within posts) plugin and there are many derivatives of it. And there are a couple which are very close to each other in that only some text (mainly credit text) in the options menu is changed! I absolutely don’t intend to do something like that.
I’ve actually been referred to this plugin by a friend and over time have realised it is widely used in some countries other than my own.
Just to inform guys of my intention and the action which I’m hoping to take…
I’ve noticed that the particular plugin I am interested in is still widely used, last updated 3 years ago and it started out as a ‘WordPress enhancement plugin’ (i.e. To enhance the features of WordPress). As versions went on, the developers seemed to have started a company and created an API for there online venture company which they added to the plugin.
Unfortunately the company closed down, the developers split up and seem to not want to get involved now (that’s my opinion).
The plugin is still used by many and people seem to want support for it.
I intend to strip the API feature out of it (the company is closed, websites down, API doesn’t function anymore) and utilise the core ‘WordPress enhancing’ features of the plugin.
Then make my own additions to the plugin as well. I have been using this plugin and have already made personal modifications to it which is the derivative I wish to publish.
I don’t have any issue with giving credit where it is due and would have preferred to work with the developers rather than take what I call a ‘cold’ credit route.
When I say ‘takeover’ its simply because I feel that if there are users of this plugin who need support and the plugin has potential so I felt that would be easiest, most convenient route possible.
Thanks again!
