[Gambas-devel] Provide special auto-instance of a class

[Benoît Minisini]

Le 05/04/2012 01:25, tobi a écrit :
> Me again,
>
> ...
>
> I wonder what's wrong with this:
>
> GB_DESC CWindowDesc[] = { GB_DECLARE("Window", sizeof(struct
> nc_window)), ... GB_METHOD("_new", NULL, CWindow_new,
> "(x)i(y)i(w)i(h)i"), ... };
>
> GB_DESC CStdscrDesc[] = { GB_DECLARE("Stdscr", sizeof(struct
> nc_window)), GB_INHERITS("Window"), GB_AUTO_CREATABLE(),
>
> GB_METHOD("_new", NULL, CStdscr_new, NULL),
>
> GB_END_DECLARE };
>
> It gives a "Not enough arguments" error as soon as I use the Stdscr
> class, thus on its auto-creation. If i replace GB_AUTO_CREATABLE()
> with GB_NOT_CREATABLE() the program starts but of course I can't do
> anything with its properties (wait a minute, not-creatable means that
> _new() isn't called at all?). I am able to overwrite the inherited
> function? I'm sure I misunderstand something about inheritance or
> those IDs. Could anyone point me to the right way?
>
> Regards, Tobi
>

Because all constructors all called when you use inheritance, and each
constructor consume arguments. This is explained in the "Gambas object
model" page on the wiki.

So I suggest you do differently, as I did in the gb.db component.

In the gb.db component, you have a Connection class and a DB static
class that has the same methods and properties as the Connection class,
except that they are all static.

So:

1) Make your 'Window' class as you did.

2) Create a 'StdScr' class with the same methods and properties, except
that everything is static.

3) Both Window and StdScr use the same implementation method.

4) In the implementation method, just check the "_object" argument. If
it is not null, then you are dealing with a Window object. If it is
null, then you are dealing with the StdScr class.

Was I clear?

-- 
Benoît Minisini