Re: How to clear/replace filter list in File Chooser?

[Toralf Lund <toralf procaptura com>]

Toralf Lund wrote:
> Does anyone here know how to clear the list of user selectable filters 
> from a file selector and/or replace the list with a new one? Or 
> differently put, can someone spot the mistake(s) in the code included below? 
>   
> [ ... ]
>   
I think I can answer that question myself, now. The problem is that the 
filter is set up as a temporary object (on the stack), where it 
apparently must be allocated - because add_filter() stores a reference 
to it. In other words,
>   
>   if(!validExtensions.empty()) {
>     Gtk::FileFilter extFilter;
>   
>     ... 
>     
>     
>     add_filter(extFilter);
>     
>     set_filter(extFilter);
>   }
> }
>   
should be changed to
>   
>   if(!validExtensions.empty()) {
>     Gtk::FileFilter *extFilter=new Gtk::FileFilter;
>
>     ... 
>     
>     
>     add_filter(*extFilter);
>     
>     set_filter(*extFilter);
>   }
> }
I had somehow concluded that add_filter would copy data rather than 
store a reference. Not sure why, but it seems clear now that I was wrong.

What strikes me as odd, though, is that the application wouldn't crash 
right away (as the temporary Gtk::FileFilter was destroyed), but worked 
just fine until it tried to remove the filters in order to set up a new 
list at a much later stage.

I'm also wondering why add_filter() takes a const reference when the 
FileChooser actually takes ownership of the object and may destroy it 
automatically, according to the docs (I also overlooked that bit of 
information earlier ;-() Seems like most adds in Gtk uses non-const 
references in such cases...

- Toralf