Date: Sat, 10 Sep 2005 17:02:54 -0300
From: romildo at uber.com.br
To: lablgtk at math.nagoya-u.ac.jp
Subject: Implementing gtk_plot_canvas_plot_new(GtkPlot * plot)
Message-ID: <20050910200253.GA26631 at malaquias>
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Hello.

I want to wrap the following C function

  GtkPlotCanvasChild *
  gtk_plot_canvas_plot_new(GtkPlot *plot);
                           ^^^^^^^^^^^^^

from the gtk+extra library. Note that it expects
a GtkPlot widget as argument.

I already have the following:

----------> In ml_gtkextra.c:

#define GtkPlot_val(val) check_cast(GTK_PLOT,val)
#define GtkPlotCanvasPlot_val(val) check_cast(GTK_PLOT_CANVAS_PLOT,val)

CAMLprim value ml_gtk_plot_new_with_size (value width, value heigth)
{
   return Val_GtkWidget_sink(gtk_plot_new_with_size(NULL,
						    Double_val(width),
						    Double_val(heigth)));
}

ML_1 (gtk_plot_canvas_plot_new, GtkPlot_val, Val_GtkWidget_sink)

----------> In gtkExtra.ml:

type plot             = [Gtk.widget|`plot]
type plot_canvas_plot = [Gtk.widget|`plot_canvas_plot]

module Plot = struct
  external create : float -> float -> plot Gtk.obj = "ml_gtk_plot_new_with_size"
end

module PlotCanvasPlot = struct
  external create : plot Gtk.obj -> plot_canvas_plot Gtk.obj = "ml_gtk_plot_canvas_plot_new"
end

----------> In gExtra.ml

class plot obj = object
  inherit GObj.widget (obj : GtkExtra.plot Gtk.obj)
end

let plot width heigth ?packing ?show () : plot =
  let w = Plot.create width heigth in
    GObj.pack_return (new plot w) ~packing ~show

class plot_canvas_plot obj = object
  inherit GObj.widget (obj : GtkExtra.plot_canvas_plot Gtk.obj)
end

let plot_canvas_plot plot ?packing ?show () : plot_canvas_plot =
  let w = PlotCanvasPlot.create plot in
    GObj.pack_return (new plot_canvas_plot w) ~packing ~show

----------> In test-extra.ml

let plot = GExtra.plot 0.65 0.45 ()
let child = GExtra.plot_canvas_plot plot ()

----------

When compiling test-extra.ml, I get the error:

$ ocamlc -i lablgtk.cma gtkInit.cmo gExtra.cmo lablgtkextra.cma test-extra.ml -o test-extra
File "test-extra.ml", line 13, characters 36-40:
This expression has type GExtra.plot but is here used with type
  GtkExtra.plot Gtk.obj = GtkExtra.plot Gobject.obj

How should the function GExtra.plot_canvas_plot be defined?
This function is to construct a new plot_canvas_plot object.
Any help?

Romildo