Re: could not find signal invocation hint

[muppet <scott asofyet org>]

On Nov 28, 2005, at 1:09 PM, James Muir wrote:

> I am trying to subclass a subclass of a Gnome2::Canvas::Group, and  
> I can't get a method to call its parent method. I understand that  
> SUPER:: is not available, but the online documentation baffles me  
> and I'm getting the "could not find signal invocation hint" error.  
> I've tried alot of things without success, even fiddling with the  
> signal param_types. Here is my test case. I've made this case as  
> small as I could get it.

It's not merely that SUPER:: is not available for Glib::Object  
methods --- you're confusing events, C vfuncs, and normal perl methods.

SUPER *is* available for plain old perl methods.  Since you're  
creating Fruit::ripen as a plain old perl method, overriding it from  
perl in Orange, and calling it from perl, all of the standard perl  
tricks are available.


> package main;
...
> my $fruit = Gnome2::Canvas::Item->new($canvas->root,'Orange',x=>0,  
> y=>0);
>
> $fruit->ripen();
...
> package Fruit;
...
> sub ripen
> {
...
> }
...
> package Orange;
...
> use Glib::Object::Subclass
>  Fruit::,
>  #  Unsure how to fiddle with the signals in this case. ???
>    signals=>{
>       event => \&ripen,

This doesn't do what you think it does.  This sets up Orange::ripen()  
to be called for every emission of Gnome2::Canvas::Item's "event"  
signal --- however, you're calling $fruit->ripen directly, which is  
completely different.  In that case, there is no signal emission, so  
there is no invocation hint for signal_chain_from_overridden() to  
look up to figure out whom to call.

Remove this signal setup.


>    },
...
> sub ripen
> {
>    my $self = shift(@_);
>
>    my $rect = Gnome2::Canvas::Item->new($self,'Gnome2::Canvas::Rect',
>                        x1=>110, y1=>110,
>                        x2=>150, y2=>150,
>                        fill_color=>$self->get('color'));
>
>    $self->signal_chain_from_overridden; # Produces the error.

   $self->SUPER::ripen;  # does what you want.




--
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