Python 3 adoption at the time of writing this book

So, thanks to new, exciting features, is Python 3 well adopted among its community? It's hard to say. The once-popular page, Python 3 Wall of Superpowers (https://python3wos.appspot.com), that tracked the compatibility of the most popular packages with the Python 3 branch was, at the beginning, named Python 3 Wall of Shame.

The site is no longer maintained, but in the list from the last time it was updated, on April 22, 2018, it shows that exactly 191 from 200 of the most popular Python packages at that time were compatible within Python 3. So, we can see that Python 3 seems to be finally well-adopted in the community of open source Python programmers. Still, this does not mean that all teams building their applications are finally using Python 3. At least, since most of the popular Python packages are available in Python 3, the popular excuse packages that we use have not been ported yet is no longer valid.

The main reason for such a situation is that porting the existing application from Python 2 to Python 3 is always a challenge. There are tools such as 2to3 that can perform automated code translation, but they do not assure that the result will be 100% correct. Also, such translated code may not perform as well as in its original form without manual adjustments. Moving existing complex code bases to Python 3 might involve tremendous effort, and a cost that some organizations may not be able to afford. Fortunately, such costs can be split over time. Some good software architecture design methodologies, such as service-oriented architecture or microservices, can help to achieve this goal gradually. New project components (services or microservices) can be written using the new technology, and existing ones can be ported one at a time.

In the long run, moving to Python 3 can have only beneficial effects on a project. According to PEP 404, there won't be another 2.8 release in the 2.x branch of Python, and the official end-of-life for Python 2 is scheduled for 2020. Until that time, we can expect only patch version updates for major security issues, but nothing more. Also, there may be a time in the future when all major projects, such as Django, Flask, and NumPy will drop any 2.x compatibility and will be available only in Python 3. Django has already made that step, and since version 2.0.0 was released, it no longer supports Python 2.7.

My personal opinion on this topic can be considered controversial. I think that the best incentive for the community would be to completely drop Python 2 support when creating new packages. This, of course, limits a range of such software, but may be the only right way to change the way of thinking in those who insist on sticking to Python 2.x.

We'll take a look at the main differences between Python 3 and Python 2 in the next section.