How to write Python code that is able to properly require a minimal python version?

Question

I would like to see if there is any way of requiring a minimal python version.

I have several python modules that are requiring Python 2.6 due to the new exception handl

Answer 1

To complement the existing, helpful answers:

You may want to write scripts that run with both Python 2.x and 3.x, and require a minimum version for each.

For instance, if your code uses the argparse module, you need at least 2.7 (with a 2.x Python) or at least 3.2 (with a 3.x Python).

The following snippet implements such a check; the only thing that needs adapting to a different, but analogous scenario are the MIN_VERSION_PY2=... and MIN_VERSION_PY3=... assignments.

As has been noted: this should be placed at the top of the script, before any other import statements.

import sys

MIN_VERSION_PY2 = (2, 7)    # min. 2.x version as major, minor[, micro] tuple
MIN_VERSION_PY3 = (3, 2)    # min. 3.x version

# This is generic code that uses the tuples defined above.
if (sys.version_info[0] == 2 and sys.version_info < MIN_VERSION_PY2
      or
    sys.version_info[0] == 3 and sys.version_info < MIN_VERSION_PY3):
      sys.exit(
        "ERROR: This script requires Python 2.x >= %s or Python 3.x >= %s;"
        " you're running %s." % (
          '.'.join(map(str, MIN_VERSION_PY2)), 
          '.'.join(map(str, MIN_VERSION_PY3)), 
          '.'.join(map(str, sys.version_info))
        )
      )

If the version requirements aren't met, something like the following message is printed to stderr and the script exits with exit code 1.

This script requires Python 2.x >= 2.7 or Python 3.x >= 3.2; you're running 2.6.2.final.0.

^{Note: This is a substantially rewritten version of an earlier, needlessly complicated answer, after realizing - thanks to Arkady's helpful answer - that comparison operators such as > can directly be applied to tuples.}