I told my boss I had an idea for a program that could improve efficiency across much of the business, and he let me build it on company time. In the long term, he wanted to be able to sell it to other companies. However, the program never got implemented due to personnel mismanagement, and I’d rather be able to post it on my github under a free licence so I can use it as a resume item, and at least someone would have the chance to actually use it. It’s all still in my head, and I could write it again if I wanted. If I do, is it illegal to publish it? What if I write it in a different language? Do I need to change the variable names? I did plenty of research and planning on company time to build it, and it’s not like I can research it again, it’s all still in my head.
You’re sort of missing the point. Two programming implementations are never the same if you rewrite them from scratch for anything but the most trivial program. It wouldn’t be a copy of the original and it would have a unique, if similar, implementation. It’s not as clear cut as you suggest (at least not for the reasons you suggest, but IANAL.)
It is not about the code line by line, but the functionality that OP created for their employer. And yes it is not clear-cut in the sense that in Oracle vs. Google it was AFAIK decided that the idea of the
toStringMethod does not fall under copyright. However, a software that fills a specific need for a company and is then re-implemented/released by an employee? You can bet your ass you are in for at least a lengthy battle in court.