I recently played with a plugin which I liked a lot, but felt it was missing something. So as first stage I went and wrote a tiny plugin (my first), that just added the needed feature – meaning, that the original plugin still had to be installed for something to work.
Now I gave credit to the authors for doing most of the job, but I have to think of the future, what happens if they decided to stop developing that plugin or don’t resolve issues regarding it. My plugin will stop working or will potentially become incompatible with future WordPress versions.
Would it be ethical for me to just avoid the issue alltogether by copying their code into mine and renaming the plugin functions? This of course causes other problems, but now they are my problem to resolve.
What say you?
I’m assuming for now that the plugin is open source. If so …
Most devs appreciate contributions from the community. Contact the original authors and offer your code as a patch to add your new feature.
Optionally, you can just hope that they keep developing the system and offer your smaller plugin as an extension. Just be sure to keep it up-to-date with a list of compatible WP versions and the 3rd party plugin versions.
Open source software is meant to be extended, adapted, and distributed. You have the right under most OS licenses to edit and redistribute the software so long as you follow a certain set of rules (i.e. maintaining original copyrights, releasing under a compatible license). I can’t speak to specifics without knowing which plugin you’re using, but in the majority of cases forking the plugin and releasing your own version is 100% acceptable.