Re: How to use a signal

[José Alburquerque <jaalburquerque cox net>]

Jamiil Abduqadir wrote:
> Hey again folks, continuing with the my previous posting about 
> handling Entry boxes empty, I am using
>
> Glib::SignalProxy1< bool,GdkEventFocus* > 
> Gtk::Widget::signal_focus_out_event()
>
> to check when the user leaves the box empty, but I am getting some 
> errors at compile time, can anyone help!!??
>
> namespace jve{
> Entry{
>       .......
>       Gtk::Entry* text_box;
> public:
>       MyClass();
>       .........
>       void onBlanck();
> };
> }
> jve::Entry::Entry(){
>       ....
>       text_box  = Gtk::manage(new Gtk::Entry());
>       
> text_box->signal_focus_out_event().connect(sigc::ptr_fun(&onBlank)); 
> <== here is the problem
>       ....
> }

Your problem is that you should be using sigc::mem_fun(...) instead of 
sigc::ptr_fun(...).  HTH.

-Jose

> void jme::Entry::onBlank(){ // this->getText() returns a Gtk::ustring 
> object
>    if(this->getText(().empy()){
>       // Display a Dialogbox explaining the problem
>       text_box->grab_focus();
>    }
> }
>
> D:\c++\entry.cpp||In member function `void jve::Entry::Entry()':|
> D:\c++\entry.cpp|12|error: ISO C++ forbids taking the address of an 
> unqualified or parenthesized non-static member function to form a 
> pointer to member function.  Say `&jme::Entry::onBlank'|
> D:\c++\entry.cpp|12|error: no matching function for call to 
> `ptr_fun(void (jve::Entry::*)())'|
> ||=== Build finished: 2 errors, 0 warnings ===|
>
>
> Thanks in advance
> --
> Happiness has many doors, and when one of them closes another opens, 
> yet we spent so much time looking at the one that is shut that we 
> don't see the one that just opened.
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--
José Alburquerque
jaalburquerque cox net

The path to real wisdom begins with a deep loving respect for the ever living God (Prov. 1:7)