Re: [Vala] Extension Methods

[Frederik <scumm_fredo gmx net>]

Feng Yu wrote:
> What about this:
>
> public extend class Gtk.Widget {
>     public bool set_gl_capability (GdkGl.Config glconfig,
> Gdk.GlContext? share_list, bool direct, int render_type) {
>
>       // do stuff.
>     }
> }
>
> AKA, when vala encounters the extend keyword, instead of panicing
> duplicated class declarations, it simply add the decleration to the
> existing class.

'extend' could be confused with subclassing (for example Java uses the
'extends' keyword for subclassing).

I know this feature from Objective C, where it's called "categories":
http://en.wikipedia.org/wiki/Objective_c#Categories

These 'categories' are even named, so you can group these additional
methods thematically. If Vala considers such a feature I would propose
the following syntax:

 public class string category SpellChecking {
     // ...
 }

 public class Gtk.Widget category GLFunctionality {
     public bool set_gl_capability (...) {
         // do stuff.
     }
     // ...
 }

These category names would get lost in C code, but they could be nice
additional information in a Vala object browser.


Regards,

Frederik