Re: Mapping of model attributes with unknown values to a corresponding widget display

[Markus Elfring <Markus Elfring web de>]

> That method's documentation mentions that you can instead create the
> TreeView::Column manually and use TreeViewColumn::set_cell_data_func()
> with your own callback slot, which you could use to set the
> "inconsistent" property:
> http://developer.gnome.org/gtkmm/unstable/classGtk_1_1CellRendererToggle.html#a680f8f0b502d82a6c909aafe90284026

I hope that a related method overload exists already in a "convenience library".


> 
>> How do you store a "NULL" (SQL) for a model attribute with a data type like
>> "bool" and update its visual appearance accordingly?
> 
> Obviously C++'s bool type can't represent 3 values. You would need
> something else, I suppose.

I know that, too ... - I'm just looking for general programming interfaces which
make the handling of model attributes with unknown values a bit more convenient.


> Personally, I use Gnome::Gda::Value, from libgda, via libgdamm.
> It's not wonderful, but it works. 

I find the documentation for this class incomplete.
http://developer.gnome.org/libgdamm/4.99/classGnome_1_1Gda_1_1Value.html

Can such a class be used without the complete database abstraction library?

Regards,
Markus