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As a classic MacOS developer back in the day, "publish and subscribe" doesn't mean what you probably think it does. It isn't like "publish and subscribe" in Javascript or similar.

In classic MacOs "publish and subscribe" was a kind of real-time clipboard which allowed you to paste contents from one application in to another and have it updated in real-time if you edited the source file. The idea was interesting, but it created odd interactions and corner cases that weren't nice. It was also very slow and buggy in practice. Not many applications supported it, and those that did didn't support it well in my opinion.

https://en.wikipedia.org/wiki/Publish_and_Subscribe_(Mac_OS)