Re: Hoe to create Singleton objects with GObjects ?

[Emmanuele Bassi <ebassi gmail com>]

hi;

I assume you're referring to the C bindings for GObject.

On Tue, 2007-06-26 at 20:11 +0530, Gautam Ravi wrote:

> I dont know whether this is the right place to ask this question, I
> could not find any other list. Please excuse ;-)
> 
> I have two things to ask,
> 
> 1. Is it possible to create singleton objects in GObjects ? 

yes, there are two methods.

  1. you provide a foo_object_new() function and store the pointer
     g_object_new() returns inside a static variable, and for any
     subsequent call you return that pointer;
  2. you override the GObjectClass::constructor() vfunc and you
     store the pointer of the new instance there, returning the
     same instance.

the second method has the advantage that it works even if you call
g_object_new(FOO_TYPE_OBEJCT, NULL) directly instead of passing through
your own constructor function.

> 2. Is it possible to create a final class ? (i.e A class which cannot
> be derived) in GObjects?

yes. typedef your struct inside the header file, but define it inside
your c source file. if someone tries to subclass that object the
compiler will print an error because the type is incomplete.


-- 
Emmanuele Bassi,
W: http://www.emmanuelebassi.net
B: http://log.emmanuelebassi.net