check_version.py revision 9f3660fabcee422e88c0cd5afe8ab8c5f6ed1e47 
1# This file must use Python 1.5 syntax.
2import sys, string, os, glob, re
3
4
5def extract_version(path):
6    match = re.search(r'/python(\d+)\.(\d+)$', path)
7    if match:
8        return (int(match.group(1)), int(match.group(2)))
9    else:
10        return None
11
12
13def find_desired_python():
14    """Returns the path of the desired python interpreter."""
15    pythons = []
16    pythons.extend(glob.glob('/usr/bin/python2*'))
17    pythons.extend(glob.glob('/usr/local/bin/python2*'))
18
19    possible_versions = []
20    best_python = (0, 0), ''
21    for python in pythons:
22        version = extract_version(python)
23        if version >= (2, 4):
24            possible_versions.append((version, python))
25
26    possible_versions.sort()
27
28    if not possible_versions:
29        raise ValueError('Python 2.x version 2.4 or better is required')
30    # Return the lowest possible version so that we use 2.4 if available
31    # rather than more recent versions.  This helps make sure all code is
32    # compatible with 2.4 when developed on more recent systems with 2.5 or
33    # 2.6 installed.
34    return possible_versions[0][1]
35
36
37def restart():
38    python = find_desired_python()
39    sys.argv.insert(0, '-u')
40    sys.argv.insert(0, python)
41    os.execv(sys.argv[0], sys.argv)
42
43
44def check_python_version():
45    version = None
46    try:
47        version = sys.version_info[0:2]
48    except AttributeError:
49        pass # pre 2.0, no neat way to get the exact number
50    if not version or version != (2, 4):
51        restart()
52