How to know that the interpreter is Jython or CPython in the code?

Question

Is there a way to detect that the interpreter that executes the code is Jython or CPython?

I have another post: Jython does not catch Exceptions. For this case, if I know the interpreter is Jython, I can have different code that should work.

if JYTHON:
    sys.path.insert(0, os.path.dirname(__file__))
    from utils import *
else:
    from .utils import *

Python is the language specification. The most well known implementations are Jython and **CPython**. — Jayanth Koushik, Mar 10 '14 at 16:14
@JayanthKoushik: So, is your point that there is no (easy or programatic) way? — prosseek, Mar 10 '14 at 16:15
No no; I'm was pointing out that the interpreter is Jython or CPython, not Jython or Python. I think the edit makes it clear. — Jayanth Koushik, Mar 10 '14 at 16:19
Is the Jython executable named ```jython.exe``` or is it just ```python.exe``` — wnnmaw, Mar 10 '14 at 16:27
Also see http://stackoverflow.com/questions/1854/python-what-os-am-i-running-on — devnull, Mar 10 '14 at 16:36

Dr. Jan-Philip Gehrcke · Accepted Answer · 2014-03-10T16:27:17.453

8

There is an official way to do it! :-) Please have a look at

http://docs.python.org/2/library/platform.html#platform.python_implementation

Returns a string identifying the Python implementation. Possible return values are: ‘CPython’, ‘IronPython’, ‘Jython’, ‘PyPy’.

New in version 2.6.

I did not know that before.

Old answer:

There probably is no standardized interface, but you can use some educated guessing, based on e.g. sys.executable (http://docs.python.org/2/library/sys.html#sys.executable), and sys.version. Furthermore, some interpreters for sure provide features that are specific to them, which you can make use of.

edited Mar 10 '14 at 16:27

answered Mar 10 '14 at 16:22

Dr. Jan-Philip Gehrcke

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Note: starting from python3.3 there's also [`sys.implementation`](http://docs.python.org/3.3/library/sys.html#sys.implementation) which contains the name and version of the implementation and might contain other relevant information. – Bakuriu Mar 10 '14 at 16:33

score 1 · Answer 2 · edited May 23 '17 at 12:10

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I'm not sure this is safe way, but I got a hint from Find full path of the Python interpreter?.

With print sys.executable, I have different results.

context> jython context/context.py
None
context> python context/context.py
/usr/bin/python

So, checking sys.executable might be one way for the checking.

edited May 23 '17 at 12:10

Community

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answered Mar 10 '14 at 16:22

prosseek

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score 0 · Answer 3 · answered Mar 10 '14 at 16:26

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Might not be the best way, but to detect Jython, couldn't you just try to import something from Java?

try:
    import java.lang.System
    print "Jython!"
except:
    print "Not Jython"

answered Mar 10 '14 at 16:26

SlightlyCuban

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How to know that the interpreter is Jython or CPython in the code?

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