Re: Gtk::Editable::on_insert_text

[Antonio Coralles <noche suapie reflex at>]

[snip]

> I needed a Gtk::Entry object that behaved the same way, so I derived a 
> class I called "MaskedEntry."  from Gtk::Entry.  I added a gchar 
> pointer as a protected class variable, and as a formal paramter to the 
> contructor I passed a pointer to a gchar string containing all the 
> characters that I wanted to mask out of the entry.  The constructor 
> makes a copy of this string with g_strdup.  My class overrides the 
> "on_key_press_event" such that it uses gdk_keyval_to_unicode on the 
> event->keyval argument to convert it to a unicode value and then uses 
> strchr to see if that character is in the mask string. 

[snip]

But what happens when the user pastes something into the entry ? By 
overriding Entry::insert_text_vfunc(...) this is no problem because i 
always get the whole string which the user tries to insert ...

[snip]

> If it is not, Gtk::Entry::on_key_press_event( event ) is called, 
> passing the original argument along to the framework.  If, however, 
> the character does exist in the mask string, I put up a 
> Gtk::MessageDialog informing the user that the input character is not 
> allowed as valid entry and return without calling GtK::on_key_press_event.
> Because all this happens before any characters are inserted into the 
> text of the entry, it is neat and clean.
[snip]

By the way, when i just whant to surpress a single character, this 
soloution may be a bit complicated. Here is basically what I have done:

class SmartEntry : public Gtk::Entry
{
   public:
   typedef sigc::slot<bool, const Glib::ustring&> SlotAccept;

   //accept should return true if the string which may be inserted is 
legal, false otherwise
   void setCharacterAcceptFunc(const SlotAccept& accept);

  protected:
   //overriden insert_text_vfunc
};

This seems quite nice and flexible to me - maybe I should consider 
switching to slot<gchar, const::Glib::ustring&> so that callbacks return 
0 if OK and the value of the first rejected char otherwise. And [by 
writing this nice ideas come to my mind] maybe I should also add

typedef sigc::slot<void, gchar> SlotReject;
void setCharacterRecectFunction(const SlotReject& reject);

and supply the class with a reasonable default[eg. emmiting a beep].

Feel free to critizise,
                                 Antonio