Creating a class with all the elements specified in a file using ConfigParser

Question

I have created a .ini-like file with all the values which I need later in my program, see below:

[debugging]
checkForAbort = 10
...

[official]
checkForAbort         


        

Answer 1

self.name = value doesn't work as you expect. You might mean setattr(self, name, value) It creates instance attributes dynamicallly.

To make it a singleton you could make the instance to be a global variable in config/settings module. Initialize it once on a program startup e.g., like the logging module does it for the root logger: logging.config.fileConfig('logging.conf').

It is a common desire to use an attribute access for what is essentially a dict e.g., argparse.Namespace that carries command-line options.

You could access the config later by importing it: from mypackage.config import config, e.g., mypackage/config.py:

class Config(object):
    ...

config = Config() # empty or default config without any configuration

In mypackage/__main__.py:

from .config import config
...
# initialization code
config.update_from_file('mypackage.conf') # it might call `setattr()` inside

Note: setattr() works correctly even you set properties. __dict__.update() breaks in this case:

class XValidatorMixin(object):
    @property
    def x(self):
        return self._x

    @x.setter
    def x(self, value):
        if value < 0:
            raise ValueError
        self._x = value


class CUpdate(XValidatorMixin):
    def __init__(self, **options):
        self.__dict__.update(options)


class CSetAttr(XValidatorMixin):
    def __init__(self, **options):
        for name, value in options.items():
            setattr(self, name, value)

for C in [CUpdate, CSetAttr]:
    o = C(a=1, b=2) # non-property attributes work as expected
    assert o.a == 1 and o.b == 2

o = CSetAttr(x=1)
assert o.x == 1 # setattr also sets property

o = CUpdate(x=1)
try:
    o.x # .update() doesn't set property
except AttributeError:
    pass
else:
    assert 0


try:
    o = CSetAttr(x=-1)  # invokes property setter
except ValueError: # that correctly reject negative values
    pass
else:
    assert 0