Accessor functions for class wide datamembers/properties

[Mikoyan <miko2 pandora be>]

Hi all, I doubted where to post this question but I'll
try this list :-)

Imagine I have a DemoCarClass class structure containing
some datamembers like "tax_percentage". If want to create accessor
functions for this: how should they look like? I think
there are three possibilities:

1) like any function member of the class

E.g. demo_car_set_tax_percentage(DemoCar *self, guint tp);

The implementation of this function would call then something like:
DEMO_CAR_GET_CLASS(self)->tax_percentage = tp;

2) like any function member of the class, without the self ptr

E.g. demo_car_set_text_percentage(guint tp);

and would call something like this :
DEMO_CAR_CLASS(g_type_class_peek(DEMO_TYPE_CAR))->tax_percentage = tp;

3) something like demo_car_class_set_text_percentage
with or wihtout a DemoCarClass* ptr.

Personally I would go for 1) or 2). I think the user of a class should
NEVER touch the class structure, or should even need it.

What is the general coding convention? (I'm writing a GObject Class
Generator and I want to do it right).

Has anyone a word on this???

Greetingz, 

        Steven