Open source e-book manager Calibre author Kavid Goyal recently disclosed his requirements for users to upgrade to Python 3 in 2017 to respond to show Calibre attitude does not migrate directly to the Python 3.
In August 2017, users submitted feedback that Calibre needed to be upgraded to Python 3 because Python 2 will stop supporting in 2020. Kavid Goyal changed the status of the issue to “will not fix” and responded: “I don’t have to, I am fully capable of maintaining Python 2 myself. This is much less work than considering moving the entire code base.”
With the confirmation of Guido van Rossum’s support for Python 2.7 on January 1, 2020, Calibre has received a lot of requests for upgrades, so Kavid Goyal chose to make the previous response public for a unified response.
Also, Kavid Goyal added on GitHub, “My goal is to run Calibre’s code on Python 3 in the same way as Python 2. It is planned to be fully compatible with Python 3 by the end of 2019 or at the beginning of 2020 at the latest.”
It has been a decade since Python 3.0 was released, and many software and projects have been migrated. However, because it is not backwards compatible, some developers choose not to follow up.