Subclassing SimpleList with signals

[muppet <scott asofyet org>]

04:17AM <jodrell> morning all
04:21AM <jodrell> i've got a conundrum - i'm subclassing  
Gtk2::SimpleList, but want to add my own signals. but because  
SimpleList isn't registered with the GLib type system, i can't. is  
there a way to add signals after the startup?


SimpleList isn't registered because it's subclassed by simple perl  
reblessing.  That means there's no GType for it.  In C you probably  
could add signals after a type has been created, but we don't bind  
those functions in perl so you can't; even if you could, because  
there's no special GType for SimpleList, you'd be adding your signals  
to TreeView, which isn't what you want.


Now, there are two ways around this, so the question is, what are you  
trying to do?


a) If you need to add a signal that corresponds to something  
happening on the model, you can create your own model subclass, and  
then do

  my @ary;
  tie @ary, 'Gtk2::SimpleList::TiedList', $model;
  # fill the model
  @ary = ...;

I've often thought that this should be broken out into a more  
generally useful module, because the tied behavior really is the best  
part of the whole thing.


b) If you want to add signals to the view, then use the same  
functionality that is there to allow you to turn a glade-created  
TreeView into a SimpleList:

   my $view = MyCoolCustomTreeViewClass->new;
   my $slist = Gtk2::SimpleList->new_from_treeview ($view, ...);

And everything should Just Work.  new_from_treeview() will replace  
whatever model was already in the view with a new one.


On the other hand, if you want to add signals to both the model and  
the view, then things get a little trickier.  new_from_treeview() is  
hardcoded to create a Gtk2::ListStore, so you can't override the  
model class.  The model instance is held not only in view, but also  
in the tied instance, and, worse, in closures used for the cell  
editing signals.  In retrospect, that should be done a little more  
cleanly, fetching the model on demand from the slist instance.  So,  
without a patch to SimpleList, you can't really use a custom  
implementation for both the view and the model.


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