[Vala] overload tricks

["Martin (OPENGeoMap)" <martin opengeomap org>]

Hi:

Several weeks ago i post a questions about overload functions in VALA. I 
want create a wiki page with substitute methods in VALA for this topic:

1)))  OVERLOAD FUNCTIONS 1:
You can use default values for parameters:

void method (int param1 = 5, string param2 = "x", bool param3 = false) {
        ...
}


then you can call

method ();
method (6);
method (6, "y");
method (6, "y", true);

this is perfect to emule Visual basic parameters for example.


2))) OVERLOAD CONSTRUCTOR.

GtkWidget <http://library.gnome.org/devel/gtk/stable/GtkWidget.html>*          gtk_button_new 
<http://library.gnome.org/devel/gtk/stable/GtkButton.html#gtk-button-new>                      (void);
GtkWidget <http://library.gnome.org/devel/gtk/stable/GtkWidget.html>*          gtk_button_new_with_label 
<http://library.gnome.org/devel/gtk/stable/GtkButton.html#gtk-button-new-with-label>           (const gchar 
<http://library.gnome.org/devel/glib/stable/glib-Basic-Types.html#gchar> *label);
GtkWidget <http://library.gnome.org/devel/gtk/stable/GtkWidget.html>*          gtk_button_new_with_mnemonic 
<http://library.gnome.org/devel/gtk/stable/GtkButton.html#gtk-button-new-with-mnemonic>        (const gchar 
<http://library.gnome.org/devel/glib/stable/glib-Basic-Types.html#gchar> *label);
GtkWidget <http://library.gnome.org/devel/gtk/stable/GtkWidget.html>*          gtk_button_new_from_stock 
<http://library.gnome.org/devel/gtk/stable/GtkButton.html#gtk-button-new-from-stock>           (const gchar 
<http://library.gnome.org/devel/glib/stable/glib-Basic-Types.html#gchar> *stock_id);

How can we emule this topic in VALA:
http://www.vala-project.org/doc/references/gtk+-2.0.vapi/Gtk/Button.htm

This VALA button i think it´s a good example. 
Any samples to the wiki??


This is necessary for many classes like a "circle" class. We can create 
a circle by different kind of parameters (radius+center, 3 points, etc).


3))) OVERLOAD TYPES OF PARAMETERS

int find(int colum, table A, int value) 
int find(int colum, table A, long value) 

int find(int colum, table A, string value) 

How can we find a value in table if we have different kinds of column types.
Perhaps here we don´t have any solution, or perhaps using pointers.


--
Regards.
Martin