Re: [Vala] Singleton question

["Phil Housley" <undeconstructed gmail com>]

2008/10/29 Ali Sabil <ali sabil gmail com>:
> You can take a look at this:
> http://live.gnome.org/Vala/Tutorial#head-a81a520acce1ad8622b8a2f895177b9765a69841
>
> Also, maybe you should read this:
> http://steve.yegge.googlepages.com/singleton-considered-stupid

Since that article has no comments section, I'll say this here:  What?
 There was really no coherent argument there at all.  Singleton is
fine where the size of the project makes it appropriate - for
enterprise level stuff it will cause problems, but how much of life is
that?  Used well a singleton represents some functionality that isn't
directly tied to any particular data, while still allowing the
flexibility of OO programming, despite what the article says, of
course you can subclass a singleton, it's just another class after
all.

Anyway, that's not the point of this thread.  Basically all you have
to do to make your singleton threadsafe is remember that anyone can
call it at any time, regardless of how long ago they called
get_instance.  That means you either have to make sure every call to a
method that can change data is locked (see the tutorial, as Ali said)
or move to an asynchronous model (probably not worth the effort unless
some singleton operations are really very long.)

Phil.

> --
> Ali
>
> On Wed, Oct 29, 2008 at 6:28 AM, "José D. Abad" <granveoduendes gmail com>
> wrote:
> > I used the singleton pattern. For now it has worked.
> > My question is: How can I make it//// thread-safe with Glib?
> > ________________
> > using GLib;
> >
> > public class CSingleton : Object
> > {
> >   private static CSingleton Instance = null;
> >
> >   private static void CreateInstance ()
> >   {
> >       if (Instance == null)
> >       {
> >           Instance = new CSingleton ();
> >       }
> >   }
> >
> >   public static CEscena Get_Instance ()
> >   {
> >       if (Instance == null) CreateInstance ();
> >       return Instance;
> >   }
> > }
> > ________________
> > ......
> >
> > CSingleton singleton = Get_Instance ();
> >
> > ________________
> > _______________________________________________
> > Vala-list mailing list
> > Vala-list gnome org
> > http://mail.gnome.org/mailman/listinfo/vala-list
>
>
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