wxruby users - May 2005 - ruby destructor hooks

Hi

Is there a way of finding out when or whether the wx object referenced 
in ruby is still alive?

Here''s my problem

# register that +wx_control+ should update on application events of type 
+event_type+
def add_subscriber(wx_control, app_event_type)
    @subscriptions[app_event_type].push(wx_control)
end

# later
def broadcast(app_event)
    @subscriptions[app_event.type].each { | subscriber | 
subscriber.notify(app_event) }
end


I have an application in which a ruby hash mapping subscribable 
application events (like a new document being added) to controls which 
should update their appearance on these events. Sometimes a control will 
have been closed by the user, but is still in the subscribers list. When 
an event is broadcast, its "notify" method is called, it gives a
"pure
virtual method call" error (wxruby 0.6.0).

I''ve tried several different things to clean up the subscribers list as
controls are destroyed, but without success:


WeakRef
ObjectSpace.define_finalizer(subscriber)
subscriber.evt_close() { | e | delete_subscriber(subscriber) }

The last seems to be the most promising, but it doesn''t work for all
the
control types that can be subscribers - only for frames. Is there 
something universal to all Wx controls that I could try?

cheers
alex

Alex Fenton wrote:
> Hi
> 
> Is there a way of finding out when or whether the wx object referenced
> in ruby is still alive?
(snip)
> subscriber.evt_close() { | e | delete_subscriber(subscriber) }
> 
> The last seems to be the most promising, but it doesn''t work for
all the
> control types that can be subscribers - only for frames. Is there
> something universal to all Wx controls that I could try?
The only thing I can think of is to override the destroy method for each
of the controls you want to monitor. Your implementation should remove
this control from your hash, and then must return super.

I think this will work in wxruby-swig, because I think it automatically
allows all virtual C++ methods to be overridden in ruby. It has been
long enough since I have worked with this that I could be wrong. I
suspect it won''t work with wxruby-0.6.0, but keep in mind that it has
been even longer since I have worekd with that code base.

Kevin