The second thing is that the config file can be anywhere and I do not want force people to make any Python modules (with those strange __init__.py files). They will simply forget to create.
On the other hand I want to keep those attributes in the class object because then I can use that object in other part of the program. First idea was to simply use execfile()
Here is how I overcome the problem, I create a BaseSettings class with the constructor that takes an path to the settings file:
class BaseSettings(object): def __init__(self, settings_file): """Constructor of the settings class. Args: settings_file: The full path to the settings file. """ _required_sections = set([ 'ANGLES', 'DIHEDRALS', 'PAIRS', 'ATOM_PAIRS', 'BOND_CONFIG', 'TOTAL_NUMBER_OF_CROSSLINKS' ]) settings_variables = {} copy_globals = globals().copy() try: execfile(settings_file, copy_globals, settings_variables) except SyntaxError as ex: print 'There is an error in your config file %s in line %s' % ( ex.filename, ex.lineno) print '%d: %s' % (ex.lineno, ex.text) print ex.msg sys.exit(2) # Checks if some attributes are missing in the settings file. missing_sections = _required_sections - set(settings_variables) if missing_sections: Exception( 'Invalid settings file, those sections are missing: %s' % ( ','.join(missing_sections)) # Loads the variables as it they would be and attributes of the class. self.__dict__.update(settings_variables)and then I use execfile() with the copied globals() and the empty dict settings_variables that works as the container for the locals(). I had to copy globals dict because otherwise I had those attributes in the globals.
Afterwards the variables from the settings file can be found in the settings_variables dictionary. So the only things was to update the __dict__ of the class with those variables.