[loveheaven]

Originally Posted by kovidgoyal

What is your end goal here? If you want to hack on calibre all you need to do is
set one env var to point to the location of the source code.

See https://manual.calibre-ebook.com/develop.html

I want to add some functions to Ebook-edit and I can use these functions in the editor I launch by right-click an EPUB file and select the menu "Open with ebook-edit" in the MacOS system menu.