Use two separate versions of python in the same script

Question

I have two blocks of code that I would like to combine into one python script. One block of code is written in Python 2.7, the other in Python 3.6

My question is, is there some way to call an old version of python mid script to run that specific block of code?

For instance, if I ran the following code, the script would error out because the second print statement is missing the parenthesis:

#Running python 2 and 3!!

#Py 2
print "Python 2"

#Py 3
print "Python 3"

Note: Converting the block of code written in 2.7 is possible, but will take a very long time; Time that I do not have at the moment.

There is no way to do this for two sections in the same file. You can put the second bit in another file and use subprocess.call — Phydeaux
– Phydeaux, Commented Feb 15, 2018 at 15:51
you cannot put print "Python 3" in a python 3 script, even somewhere where it's not executed. — Jean-François Fabre
– Jean-François Fabre ♦, Commented Feb 15, 2018 at 15:52
so, naughty boy, you don't put shebang on top of your scripts? -)) — marmeladze
– marmeladze, Commented Feb 15, 2018 at 15:53

Rodrigue · Accepted Answer · 2018-02-16 08:44:13Z

2

You could call your Python 2 snippet in a separate process from your Python 3 code (or vice versa) using the subprocess module. That would only work if you don't expect your Python context to be affected by the side effects of the Python 2 snippet, e.g. setting a variable from 2 that 3 will then use would not be possible.

If you wanted to use objects created by your Python 2 snippet in your Python 3 script, you could consider using pickle: serialize your objects to a local file in Python 2.7 and deserialize them from Python 3 - note that there are some changes between 2 and 3 that pickle will have to handle (see Unpickling a Python 2 object with Python 3).

edited Feb 16, 2018 at 8:44

answered Feb 15, 2018 at 17:20

Rodrigue

3,6872 gold badges42 silver badges50 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

JimmyBuffet_Express Over a year ago

Is it possible to use pickle to access the object from the subprocessed script? How about writing to a flat file, then reading it in later on in the script?

Rodrigue Over a year ago

That would work and there are some options in pickle.load just for that purpose. I'll add that option to my response.

Skandix · Accepted Answer · 2018-02-15 17:11:41Z

1

To save you time: Automated Python 2 to 3 code translation

using 2to3 have worked wonders for me and is very simple to handle:

$ 2to3 example.py

answered Feb 15, 2018 at 17:11

Skandix

2,0206 gold badges31 silver badges38 bronze badges

Collectives™ on Stack Overflow

Use two separate versions of python in the same script

2 Answers 2

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related