[Gtk-sharp-list] GTK# app "hanging"

Raúl Moratalla raul.moratalla@ono.com
Wed, 23 Feb 2005 12:58:16 +0100

Thanks again for the infor Jon :) but I have another question.
My application uses Glade# and I initialize the widgets in the constructor of 
my class:

txtServerLog = (gxml.GetWidget("txtServerLog") as TextView);
buffer = txtServerLog.Buffer;

This was working fine.
In the constructor I also add the following line:
krnGateway.OnLogMessage+= new LogEvent(OnLog);

And this are other functions that will update a widget:
private void OnLog(Constants.Log importance,string strMsg)
	Gtk.Timeout.Add(0,delegate{m_Log(this,importance,strMsg); return false;});
private void m_Log(object sender,Constants.Log importance,string strMsg)
	if (strMsg.Length==0) return;
	string newline=DateTime.Now.ToShortTimeString()+" "+strMsg+"\n";
	buffer.Text = buffer.Text + newline;

The objects buffer and txtServerLog are initialized but when my application 
starts it crashes whith the following error:

Unhandled Exception: System.NullReferenceException: Object reference not set 
to an instance of an object
in [0x0003b] (at /home/raul/lphantGTK/Servers.cs:170) 
eLePhantGTK.TServers:m_Log (object,eLePhant.Types.Constants/Log,string)
in <0x00019> <>AnonHelp<0>:<#AnonymousMethod>0 ()
in <0x0003b> (wrapper delegate-invoke) System.MulticastDelegate:invoke_bool ()
in <0x0000e> GtkSharp.FunctionWrapper:NativeCallback (intptr)
in <0x00029> (wrapper native-to-managed) 
GtkSharp.FunctionWrapper:NativeCallback (intptr)
in (unmanaged) 0x40080ca5
in <0x00004> (wrapper managed-to-native) Gtk.Application:gtk_main ()
in <0x00007> Gtk.Application:Run ()
in [0x00095] (at /home/raul/lphantGTK/Main.cs:161) 
eLePhantGTK.eLePhantGTK:.ctor (string[])
in [0x00001] (at /home/raul/lphantGTK/Main.cs:138) 
eLePhantGTK.eLePhantGTK:Main (string[])

It is due to the line: buffer.Text = buffer.Text + newline;
If I initalized the buffer object why does this happen?

El Martes, 22 de Febrero de 2005 23:58, Jonathan Pryor escribió:
> On Tue, 2005-02-22 at 23:16 +0100, Raúl Moratalla wrote:
> > Thanks for your info Jon but I have the following question.
> > I added a line like this in my program:
> >
> > Gtk.Timeout.Add(0,delegate{m_Log(this,importance,strMsg);});
> >
> > If I compile my program I get the following error:
> > Not all code paths return a value in anonymous method of type
> > `Mono.CSharp.AnonymousMethod'(CS1643)
> >
> > What am I doing wrong?
> Let's follow the types...  Gtk.Timeout.Add is declared as:
> 	public delegate bool Gtk.Function ();
> 	public class Gtk.Timeout {
> 		public static uint Add (uint interval, Function function);
> 	}
> Basically, the delegate passed to Gtk.Timeout.Add is expected to return
> a `bool'.  Your delegate doesn't, resulting in the compiler error.
> To fix this, return a value from your anonymous delegate (I return
> `false' because the return value specifies whether or not the delegate
> should be called again, and I assume you don't want it called again):
> 	Gtk.Timeout.Add (0, delegate {
> 		m_Log (this, importance, strMsg);
> 		return false;
> 	});
>  - Jon
> _______________________________________________
> Gtk-sharp-list maillist  -  Gtk-sharp-list@lists.ximian.com
> http://lists.ximian.com/mailman/listinfo/gtk-sharp-list