Checking Version of Python Interpreter Upon Execution of Script With Invalid Syntax

Question

I have a Python script that uses Python version 2.6 syntax (Except error as value:) which version 2.5 complains about. So in my script I have included some code to check for the Python interpreter version before proceeding so that the user doesn't get hit with a nasty error, however, no matter where I place that code, it doesn't work. Once it hits the strange syntax it throws the syntax error, disregarding any attempts of mine of version checking.

I know I could simply place a try/except block over the area that the SyntaxError occurs and generate the message there but I am wondering if there is a more "elegant" way. As I am not very keen on placing try/except blocks all over my code to address the version issue. I looked into using an __ init__.py file, but the user won't be importing/using my code as a package, so I don't think that route will work, unless I am missing something...

Here is my version checking code:

import sys
def isPythonVersion(version):
    if float(sys.version[:3]) >= version:
        return True
    else:
        return False

if not isPythonVersion(2.6):
    print "You are running Python version", sys.version[:3], ", version 2.6 or 2.7 is required. Please update. Aborting..."
    exit()

Tony Veijalainen · Accepted Answer · 2010-09-21 16:34:21Z

16

Something like this in beginning of code?

import sys
if sys.version_info<(2,6):
    raise SystemExit('Sorry, this code need Python 2.6 or higher')

answered Sep 21, 2010 at 16:34

Tony Veijalainen

5,56525 silver badges32 bronze badges

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

2 Comments

michael.bartnett Over a year ago

Use something with this, it's what sys.version_info exists for.

JJC Over a year ago

I had a similar problem and also had tried this approach, but, unfortunately, this trick does not work in cases where the code uses syntax that is not compatible with the version of python running. This is because the interpreter checks the syntax of your code before compiling/running it. So, the "if ..." statement will never be run if, say, you have some statement elsewhere in your code that isn't compatible with the current version of python (e.g., print(..., file=sys.stderr), where the 'file' keyword is not compatible with older python.

bstpierre · Accepted Answer · 2010-09-21 12:20:13Z

15

Create a wrapper script that checks the version and calls your real script -- this gives you a chance to check the version before the interpreter tries to syntax-check the real script.

answered Sep 21, 2010 at 12:20

bstpierre

31.5k16 gold badges74 silver badges105 bronze badges

1 Comment

javawizard Over a year ago

How is it unnecessary? The entire module is syntax checked before a single line of code is run, so it's not possible to catch SyntaxError or perform version checks before it's too late without a wrapper script.

eumiro · Accepted Answer · 2010-09-21 12:14:21Z

9

In sys.version_info you will find the version information stored in a tuple:

sys.version_info
(2, 6, 6, 'final', 0)

Now you can compare:

def isPythonVersion(version):
    return version >= sys.version_info[0] + sys.version_info[1] / 10.

answered Sep 21, 2010 at 12:14

eumiro

214k36 gold badges307 silver badges264 bronze badges

2 Comments

Stunner Over a year ago

Thanks but I already have a method of checking this, shown above.

Bill Kidd Over a year ago

This would not be reliable, as the division behaves differently between 2 and 3, For example 2.6 would not be equal to 2 + (6/10). 2 + (6/10)= 2.0

Katriel · Accepted Answer · 2010-09-21 12:25:57Z

1

If speed is not a priority, you can avoid this problem entirely by using sys.exc_info to grab the details of the last exception.

answered Sep 21, 2010 at 12:25

Katriel

124k19 gold badges141 silver badges172 bronze badges

Collectives™ on Stack Overflow

Checking Version of Python Interpreter Upon Execution of Script With Invalid Syntax

4 Answers 4

2 Comments

1 Comment

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

2 Comments

1 Comment

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related