From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,WEIRD_PORT
	autolearn=ham autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,83e6a30aa3ca4e22
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2001-04-16 14:10:05 PST
Path: 
 supernews.google.com!sn-xit-03!supernews.com!cyclone-sjo1.usenetserver.com!news-out-sjo.usenetserver.com!cyclone.bc.net!logbridge.uoregon.edu!hammer.uoregon.edu!skates!not-for-mail
From: Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov>
Newsgroups: comp.lang.ada
Subject: Re: Ada newbie!
Date: 16 Apr 2001 16:58:32 -0400
Organization: NASA Goddard Space Flight Center
Message-ID: <u4rvoo93b.fsf@gsfc.nasa.gov>
References: <3ADB4F1C.AA362C9E@ida.his.se>
NNTP-Posting-Host: anarres.gsfc.nasa.gov
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Trace: skates.gsfc.nasa.gov 987455610 27685 128.183.220.71 (16 Apr 2001
 21:13:30 GMT)
X-Complaints-To: dscoggin@cne-odin.gsfc.nasa.gov
NNTP-Posting-Date: 16 Apr 2001 21:13:30 GMT
User-Agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/20.6
Xref: supernews.google.com comp.lang.ada:6927
Date: 2001-04-16T21:13:30+00:00
List-Id: <comp.lang.ada>

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