Re: Ada newbie!

[Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov>]

Michael Andersson <a98mican@ida.his.se> writes:

> Hi!
> Can somebody please help me convert the following c statement to Ada?
> gtk_widget_draw(GTK_WIDGET(glarea), NULL);
> 
> I tried
> Gtk.Widget.Draw(glarea, NULL);
> but I get the following error:
> expected type access to "Gtk_Widget_Record" defined at
> gtk-widget.ads:226
> setup_gl.adb:88:26: found type "MyGLArea" defined at line 15

This error message is telling you that you should do:

Gtk.Widget.Draw (Gtk_Widget_Record (glarea)'access, null);

Note that it said "expected type access to Gtk_widget_Record"; thus
you need the type conversion and access attribute. The C code has a
type conversion also; apparently the C types are pointer types, while
the Ada type Gtk_Widget_Record is not an access type.

Learning to read error messages carefully is an important skill.
Unfortuneately, it is not a skill textbooks get into, because it is
highly compiler-dependent. So feel free to post here with other error
messages, provided you really have tried to read it yourself.

-- 
-- Stephe