config.py

import sys, re

def read(filename):
    config = {}
    with open(filename) as fp:
        for line in fp:
            line = line.strip()
            line = re.sub(r'#.*$', '', line) # remove comments
            found = re.match(r'^([a-zA-Z0-9-_]*)\s*=\s*(.*)$', line)
            if found:
                name = found.group(1)
                value = found.group(2).strip()
                for other, replacement in config.items():
                    value = re.sub(r'\$%s\b' % other, str(replacement), value)
                if value in ['True', 'False']:
                    value = bool(value)
                else:
                    try:
                        value = int(value)
                    except:
                        try: 
                            value = float(value)
                        except:
                            pass
                config[name] = value
    return config

if __name__ == '__main__':
    print read(sys.argv[1])