|
|
|
|
.. _python3_support:
|
|
|
|
|
|
|
|
|
|
Python 3 Support
|
|
|
|
|
================
|
|
|
|
|
|
|
|
|
|
Flask and all of its dependencies support Python 3 so you can in theory
|
|
|
|
|
start working on it already. There are however a few things you should be
|
|
|
|
|
aware of before you start using Python 3 for your next project.
|
|
|
|
|
|
|
|
|
|
Requirements
|
|
|
|
|
------------
|
|
|
|
|
|
|
|
|
|
If you want to use Flask with Python 3 you will need to use Python 3.3 or
|
|
|
|
|
higher. 3.2 and older are *not* supported.
|
|
|
|
|
|
|
|
|
|
In addition to that you need to use the latest and greatest versions of
|
|
|
|
|
`itsdangerous`, `Jinja2` and `Werkzeug`.
|
|
|
|
|
|
|
|
|
|
API Stability
|
|
|
|
|
-------------
|
|
|
|
|
|
|
|
|
|
Some of the decisions made in regards to unicode and byte untilization on
|
|
|
|
|
Python 3 make it hard to write low level code. This mainly affects WSGI
|
|
|
|
|
middlewares and interacting with the WSGI provided information. Werkzeug
|
|
|
|
|
wraps all that information in high-level helpers but some of those were
|
|
|
|
|
specifically added for the Python 3 support and are quite new.
|
|
|
|
|
|
|
|
|
|
A lot of the documentation out there on using WSGI leaves out those
|
|
|
|
|
details as it was written before WSGI was updated to Python 3. While the
|
|
|
|
|
API for Werkzeug and Flask on Python 2.x should not change much we cannot
|
|
|
|
|
guarantee that this won't happen on Python 3.
|
|
|
|
|
|
|
|
|
|
Few Users
|
|
|
|
|
---------
|
|
|
|
|
|
|
|
|
|
Python 3 currently has less than 1% of the users of Python 2 going by PyPI
|
|
|
|
|
download stats. As a result many of the problems you will encounter are
|
|
|
|
|
probably hard to search for on the internet if they are Python 3 specific.
|
|
|
|
|
|
|
|
|
|
Small Ecosystem
|
|
|
|
|
---------------
|
|
|
|
|
|
|
|
|
|
The majority of the Flask extensions, all of the documentation and the
|
|
|
|
|
vast majority of the PyPI provided libraries do not support Python 3 yet.
|
|
|
|
|
Even if you start your project with knowing that all you will need is
|
|
|
|
|
supported by Python 3 you don't know what happens six months from now. If
|
|
|
|
|
you are adventurous you can start porting libraries on your own, but that
|
|
|
|
|
is nothing for the faint of heart.
|
|
|
|
|
|
|
|
|
|
Recommendations
|
|
|
|
|
---------------
|
|
|
|
|
|
|
|
|
|
Unless you are already familiar with the differences in the versions we
|
|
|
|
|
recommend sticking to current versions of Python until the ecosystem
|
|
|
|
|
caught up.
|
|
|
|
|
|
|
|
|
|
The majority of the upgrade pain is in the lower-level libararies like
|
|
|
|
|
Flask and Werkzeug and not in the actual high-level application code. For
|
|
|
|
|
instance all of the Flask examples that are in the Flask repository work
|
|
|
|
|
out of the box on both 2.x and 3.x and did not require a single line of
|
|
|
|
|
code changed.
|
