With Python 3 becoming the future of Python while Python 2 continues to be in active utilize, it is good to have your project available for both biggest releases of Python. This informative guide is supposed to guide you to figure out how better to supporting both Python 2 3 simultaneously.
If you are searching to port an extension component as opposed to pure Python signal, please see Porting Extension segments to Python 3 .
If you wish to read through one core Python creator’s take on exactly why Python 3 had become, you can read Nick Coghlan’s Python 3 Q A or Brett canon’s the reason why Python 3 prevails.
The brief ExplanationA¶
Utilize Pylint to help with making yes that you don’t regress on your Python 3 assistance ( python -m pip install pylint )
Incorporate caniusepython3 to discover which of your own dependencies include blocking their utilization of Python 3 ( python -m pip install caniusepython3 )
Once your dependencies are not any lengthier stopping your, use continuous integration to make sure you stay appropriate for Python 2 3 (tox will help check against multiple variations of Python; python -m pip install tox )
Consider using elective fixed kind examining to make sure your own sort practices works in both Python 2 3 (example. usage mypy to test your own keying in under both Python 2 Python 3; python -m pip install mypy ).
Mention: making use of python -m pip apply ensures that the pip your invoke is the one set up for your Python at this time used, whether it be a system-wide pip or one installed within an online ecosystem .
DetailsA¶
An important factor about promote Python 2 3 concurrently is you can begin these days! Even though your own dependencies commonly support Python 3 yet that doesn’t suggest you cannot modernize the signal now to aid Python 3. the majority of variations expected to support Python 3 trigger cleaner rule using more recent tactics inside Python 2 signal.
Another heavily weighed usually modernizing your Python 2 rule to additionally help Python 3 is basically computerized for your family. While you might have to make some API decisions through Python 3 making clear book facts versus binary information, the lower-level job is today mainly accomplished for both you and thus can no less than gain benefit from the automatic improvement immediately.
Keep those key points in your mind when you keep reading concerning details of porting your own laws to support Python 2 3 at 
the same time.
Drop service for Python 2.6 and olderA¶
Although you will make Python 2.5 use Python 3, it really is much easier should you decide simply deal with Python 2.7. If shedding Python 2.5 is certainly not an alternative then six venture will allow you to support Python 2.5 3 concurrently ( python -m pip install six ). Perform recognize, though, that almost all the tasks listed in this HOWTO may not be accessible to you.
If you are capable miss Python 2.5 and elderly, then your necessary variations to your rule should continue steadily to appear and feel like idiomatic Python code. At the worst you will have to incorporate a work instead of a technique sometimes or need to transfer a function as opposed to utilizing an integrated one, but otherwise the entire improvement cannot feel international to you personally.
However should shoot for merely encouraging Python 2.7. Python 2.6 has stopped being easily supported and therefore isn’t receiving bugfixes. This implies you’ll have to operate around any dilemmas you discover with Python 2.6. There are also some tools pointed out inside HOWTO which do not help Python 2.6 (age.g., Pylint), which will be common as time goes on. It’s going to merely be simpler for you in the event that you only support the versions of Python that you have to supporting.