__getattr__ for static/class variables

by

__getattr__() and __str__() for an object are found on its class, so if you want to customize those things for a class, you need the class-of-a-class. A metaclass.

class FooType(type):
    def _foo_func(cls):
        return 'foo!'

    def _bar_func(cls):
        return 'bar!'

    def __getattr__(cls, key):
        if key == 'Foo':
            return cls._foo_func()
        elif key == 'Bar':
            return cls._bar_func()
        raise AttributeError(key)

    def __str__(cls):
        return 'custom str for %s' % (cls.__name__,)

class MyClass:
    __metaclass__ = FooType

# # in python 3:
# class MyClass(metaclass=FooType):
#     pass


print(MyClass.Foo)
print(MyClass.Bar)
print(str(MyClass))

printing:

foo!
bar!
custom str for MyClass

And no, an object can’t intercept a request for a stringifying one of its attributes. The object returned for the attribute must define its own __str__() behavior.

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