Virtual functions and chaining up

[Nikhil Dinesh <nikhild seas upenn edu>]

Hi,

I'm trying to create my own object hierarchy, and I don't
understand the part in the API reference about virtual
functions and chaining up. To create a virtual public
method,  the docs say we need to do something like:

/* declaration in maman-bar.h. */
struct _MamanBarClass {
 GObjectClass parent;

 /* stuff */
 void (*do_action) (MamanBar *self, /* parameters */);
};
void maman_bar_do_action (MamanBar *self, /* parameters */);
/* implementation in maman-bar.c */
void maman_bar_do_action (MamanBar *self, /* parameters */)
{
 MAMAN_BAR_GET_CLASS (self)->do_action (self, /* parameters */);
}

I assume that the subclass definition looks like:

struct _MamanBarSubClass {
  MamanBarClass parent;

  ....

  void (*do_action) (MamanBarSub* self, /* params */);
}

If the maman_bar_do_action actually needs to do something, and
the derived class needs to chain up, wouldn't it result in another
invocation of maman_bar_do_action which is again redirected to
the derived class? This would of course result in an infinite loop.


Please clarify.

Thanks,
-Nikhil