Parse version number from python source. Really, this could be more generalized to parse any variables (given obvious restrictions) from source.

parse_version.py

import ast


def parse_version(source, name='__version__'):
    for exp in ast.parse(source).body:
        if isinstance(exp, ast.Assign) and name in (t.id for t in exp.targets):
            if len(exp.targets) != 1:
                raise ValueError('Cannot parse assignment unpacking.')
            if isinstance(exp.value, ast.Str):
                return exp.value.s
            if isinstance(exp.value, (ast.Tuple, ast.List)):
                return '.'.join(map(str, ast.literal_eval(exp.value)))
            raise TypeError('Invalid version type "{0}", must be Str, Tuple, or List.'
                            .format(type(exp.value).__name__))
        raise ValueError('Name "{0}" not found in source.'.format(name))