Re: IS_A Type Question.

[Tristan Van Berkom <vantr touchtunes com>]

Pat Suwalski wrote:
> Hello,
>
> I'm trying to recycle a callback function. The UI element comes in as a 
> GtkWidget*.
>
> The possible types I'm looking at right now are GtkCheckButton and 
> GtkCheckMenuItem. Specifically, I'm looking at an attribute they have in 
> common, "active."
>
> So, where the attribute is accessed, I'd like to assert if the object is 
> of one type or the other, and read the attribute accordingly. In a 
> language like Java, I can easily find the is_a relationship. Is there 
> something in the gtk library that will do the same? It seems like I've 
> looked everywhere! :)
In the header files of every object are the convenience macros
provided for that purpose.

There is probably a strict naming convention concerning this
but I still say consult the header is best.

usualy something like "GtkButton" type will translate to
GTK_IS_BUTTON(object) to be used as a boolean truth value.

GtkHScale    --> gtk+/gtkhscale.h -->   GTK_IS_HSCALE()
GtkLabel     --> gtk+/gtklabel.h  -->   GTK_IS_LABEL()

and so on ;-)


Cheers,
                        -Tristan