Re: How to use specific methods with a generic widget pointer?

[jody <jody xha gmail com>]

Sorry
I forgot to send this to the list

As Guillaume said, set_active is specific to Gtk::ToggleButton and
derived classes.
So if you don't want (or cant) use set_active() directly, you could
use a pointer to Gtk::ToggleButton instead of a pointer to Gtk::Widget* :
 Gtk::ToggleButton btnOK;
 Gtk::ToggleButton *ptrElement = NULL;

 ptrElement = &btnOK;

 ptrElement->set_active(true);

If your pointer sometimes points at other kinds of Widgets, you could
still use a pointer to Gtk::Widget, and then cast it to a pointer to
Gtk::ToggleButton before using it:

 dynamic_cast<Gtk::ToggleButton *>(ptrElement)->set_active(true);

Keep in mind that this will give you an error if at that moment
ptrElement does not point to a Gtk::ToggleButton (or descendant)


Jody

On Tue, Mar 17, 2009 at 3:58 PM, Paulo Flabiano Smorigo
<pfsmorigo gmail com> wrote:
> On Tue, Mar 17, 2009 at 11:40, Guillaume Brocker
> <guillaume brocker digital-trainers com> wrote:
>> Paulo Flabiano Smorigo a écrit :
>>>
>>> Hello,
>>>
>>> What can I do to solve the following error? I need to use a different
>>> kind of pointer?
>>>
>>> The code:
>>> Gtk::ToggleButton btnOK;
>>> Gtk::Widget *ptrElement = NULL;
>>>
>>> ptrElement = &btnOK;
>>>
>>> ptrElement->set_active(true);
>>>
>>> The error:
>>> error: ‘class Gtk::Widget’ has no member named ‘set_active’
>>
>> Gtk::Widget has no member ‘set_active’. This member is specific to
>> Gtk::ToggleButton and derived classes. Wy don't you call ‘btnOK.set_active’
>> directly ?
>>
>>> Thanks in advance,
>>> Paulo Flabiano Smorigo
>>
>> Guillaume
>>
>
> Hi Guillaume,
>
> Thanks for the fast reply...
>
> I know that the Gtk::Widget don't have the set_active() member but as
> it is pointing to a ToggleButton widget, isn't it possible to use the
> method?
>
> I there a someway to make the pointer accept the method?
>
> Thanks...
> Paulo Flabiano Smorigo
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