I have a Python file which might have to support Python versions < 3.x and >= 3.x. Is there a way to introspect the Python runtime to know the version which it is running (for example, 2.6 or 3.2.x
)?
This question is related to
python
Try this code, this should work:
import platform
print(platform.python_version())
Just in case you want to see all of the gory details in human readable form, you can use:
import platform;
print(platform.sys.version);
Output for my system:
3.6.5 |Anaconda, Inc.| (default, Apr 29 2018, 16:14:56)
[GCC 7.2.0]
Something very detailed but machine parsable would be to get the version_info
object from platform.sys
, instead, and then use its properties to take a predetermined course of action. For example:
import platform;
print(platform.sys.version_info)
Output on my system:
sys.version_info(major=3, minor=6, micro=5, releaselevel='final', serial=0)
Since all you are interested in is whether you have Python 2 or 3, a bit hackish but definitely the simplest and 100% working way of doing that would be as follows:
python
python_version_major = 3/2*2
The only drawback of this is that when there is Python 4, it will probably still give you 3.
To make the scripts compatible with Python2 and 3 i use :
from sys import version_info
if version_info[0] < 3:
from __future__ import print_function
Here's some code I use with sys.version_info
to check the Python installation:
def check_installation(rv):
current_version = sys.version_info
if current_version[0] == rv[0] and current_version[1] >= rv[1]:
pass
else:
sys.stderr.write( "[%s] - Error: Your Python interpreter must be %d.%d or greater (within major version %d)\n" % (sys.argv[0], rv[0], rv[1], rv[0]) )
sys.exit(-1)
return 0
...
# Calling the 'check_installation' function checks if Python is >= 2.7 and < 3
required_version = (2,7)
check_installation(required_version)
Per sys.hexversion and API and ABI Versioning:
import sys
if sys.hexversion >= 0x3000000:
print('Python 3.x hexversion %s is in use.' % hex(sys.hexversion))
Version check example below.
Note that I do not stop the execution, this snippet just:
- do nothing if exact version matches
- write INFO if revision (last number) is different
- write WARN if any of major+minor are different
import sys
import warnings
def checkVersion():
# Checking Python version:
expect_major = 2
expect_minor = 7
expect_rev = 14
if sys.version_info[:3] != (expect_major, expect_minor, expect_rev):
print("INFO: Script developed and tested with Python " + str(expect_major) + "." + str(expect_minor) + "." + str(expect_rev))
current_version = str(sys.version_info[0])+"."+str(sys.version_info[1])+"."+str(sys.version_info[2])
if sys.version_info[:2] != (expect_major, expect_minor):
warnings.warn("Current Python version was unexpected: Python " + current_version)
else:
print(" Current version is different: Python " + current_version)
The best solution depends on how much code is incompatible. If there are a lot of places you need to support Python 2 and 3, six
is the compatibility module. six.PY2
and six.PY3
are two booleans if you want to check the version.
However, a better solution than using a lot of if
statements is to use six
compatibility functions if possible. Hypothetically, if Python 3000 has a new syntax for next
, someone could update six
so your old code would still work.
import six
#OK
if six.PY2:
x = it.next() # Python 2 syntax
else:
x = next(it) # Python 3 syntax
#Better
x = six.next(it)
Cheers
Source: Stackoverflow.com