How to share function or data between APPs?

💻 Development
1

Hello,
is there a way how to share function or data between two apps? For example like “file” API in OCP?
Kind regards,
Bob

2

Not so easily, but there are ways.

What exactly are you trying to achieve?

3

Thank you Christoph,
I would like to extend Calendar app (add some tabs into the events) but as I cant find an easy solution, I decide to change calendar app directly (first idea was change few rows and everything take from 2nd app).
Kind regards,
Bob