Re: How implement an abstract class?

[Mikoyan <miko2 pandora be>]

On Thu, 2003-08-14 at 14:33, Antonio Santiago wrote: 
> Hello,

Hello

> I want to implement an abstract class with their own attributs that
> inherit all her subclasses, and her own methods, some implemented and
> somo not).
>
> Vehicle <----- Car
>
> If I create a class Vehicle and a class Car, there is nothing to avoid
> someone create a simple Vehicle's object, and then I would have an
> instance of an abstract class.

Of course it is very important that a user cannot create an instance
of an abstract class. When you register your object using
g_type_register_static in your vehicle_get_type you have to specifiy
the G_TYPE_FLAG_ABSTRACT as the last paramater : eg:

g_type_register_static (G_TYPE_OBJECT, "Vehicle", &this_info,
G_TYPE_FLAG_ABSTRACT);

Also do not provide vehicle_new() and cleary document that Vehicle
is an abstract class :-) You should be fine and users won't be
able to instantiate your astract class Vehicle.

> Some ideas.
>
> Thanks.