Re: Throwing Exceptions

From: Ignacio Machin \( .NET/ C# MVP \) ("Ignacio)
Date: 08/19/04 

Date: Thu, 19 Aug 2004 14:52:30 -0400

Hi Ron,

 I just ran it and got the same result, it does not throw the exception !
This is the first time I see this. I'm not expert in CLR code but I believe
it's Control.DoDragDrop the one that is "eating" the exceptions.

Let see if somebody else here test the code and we can know where the secret
lies.

Cheers, 

-- 
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation
"Ron Green" <Ron Green@discussions.microsoft.com> wrote in message
news:316AF1F5-8EDC-4833-85C6-BE45F053AFD5@microsoft.com...
> Here you go:
>
> using System;
> using System.Drawing;
> using System.Collections;
> using System.ComponentModel;
> using System.Windows.Forms;
> using System.Data;
>
> namespace TestDragDrop
> {
> /// <summary>
> /// Summary description for Form1.
> /// </summary>
> public class Form1 : System.Windows.Forms.Form
> {
> private System.Windows.Forms.Label lblDest;
> private System.Windows.Forms.Label lblSource;
> private System.Windows.Forms.TextBox txtSource;
> private System.Windows.Forms.Button button1;
> /// <summary>
> /// Required designer variable.
> /// </summary>
> private System.ComponentModel.Container components = null;
>
> public Form1()
> {
> //
> // Required for Windows Form Designer support
> //
> InitializeComponent();
>
> //
> // TODO: Add any constructor code after InitializeComponent call
> //
> }
>
> /// <summary>
> /// Clean up any resources being used.
> /// </summary>
> protected override void Dispose( bool disposing )
> {
> if( disposing )
> {
> if (components != null)
> {
> components.Dispose();
> }
> }
> base.Dispose( disposing );
> }
>
> #region Windows Form Designer generated code
> /// <summary>
> /// Required method for Designer support - do not modify
> /// the contents of this method with the code editor.
> /// </summary>
> private void InitializeComponent()
> {
> this.lblDest = new System.Windows.Forms.Label();
> this.lblSource = new System.Windows.Forms.Label();
> this.txtSource = new System.Windows.Forms.TextBox();
> this.button1 = new System.Windows.Forms.Button();
> this.SuspendLayout();
> //
> // lblDest
> //
> this.lblDest.AllowDrop = true;
> this.lblDest.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
> this.lblDest.Location = new System.Drawing.Point(24, 24);
> this.lblDest.Name = "lblDest";
> this.lblDest.Size = new System.Drawing.Size(320, 24);
> this.lblDest.TabIndex = 0;
> this.lblDest.DragEnter += new
> System.Windows.Forms.DragEventHandler(this.lblDest_DragEnter);
> this.lblDest.DragDrop+=new DragEventHandler(lblDest_DragDrop);
> //
> // lblSource
> //
> this.lblSource.Location = new System.Drawing.Point(32, 112);
> this.lblSource.Name = "lblSource";
> this.lblSource.Size = new System.Drawing.Size(296, 32);
> this.lblSource.TabIndex = 1;
> this.lblSource.Text = "Type in text in the text box below then drag it
> into the outlined label.";
> //
> // txtSource
> //
> this.txtSource.Location = new System.Drawing.Point(32, 152);
> this.txtSource.Name = "txtSource";
> this.txtSource.Size = new System.Drawing.Size(296, 20);
> this.txtSource.TabIndex = 2;
> this.txtSource.Text = "Your text here...";
> this.txtSource.MouseMove += new
> System.Windows.Forms.MouseEventHandler(this.txtSource_MouseMove);
> //
> // button1
> //
> this.button1.Location = new System.Drawing.Point(360, 240);
> this.button1.Name = "button1";
> this.button1.TabIndex = 3;
> this.button1.Text = "button1";
> this.button1.Click += new System.EventHandler(this.button1_Click);
> //
> // Form1
> //
> this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
> this.ClientSize = new System.Drawing.Size(504, 310);
> this.Controls.Add(this.button1);
> this.Controls.Add(this.txtSource);
> this.Controls.Add(this.lblSource);
> this.Controls.Add(this.lblDest);
> this.Name = "Form1";
> this.Text = "Form1";
> this.ResumeLayout(false);
>
> }
> #endregion
>
> /// <summary>
> /// The main entry point for the application.
> /// </summary>
> [STAThread]
> static void Main()
> {
> Application.Run(new Form1());
> }
>
> private void lblDest_DragEnter(object sender,
> System.Windows.Forms.DragEventArgs e)
> {
> if (e.Data.GetDataPresent(typeof(string)))
> e.Effect = DragDropEffects.Copy;
> else
> e.Effect = DragDropEffects.None;
> }
>
> private void lblDest_DragDrop(object sender, DragEventArgs e)
> {
>
> // uncomment the appexception line. it won't blow up. who is catching the
> error?
>
> throw new Exception("this an exception");
>
> // if (e.Data.GetDataPresent(typeof(string)))
> // {
> // string text = (string)e.Data.GetData(typeof(string));
> // this.lblDest.Text = text;
> // }
> }
>
> private void lblSource_MouseMove(object sender,
> System.Windows.Forms.MouseEventArgs e)
> {
> this.lblSource.DoDragDrop(this.lblSource.Text, DragDropEffects.Copy);
> }
>
> private void textBox1_MouseMove(object sender,
> System.Windows.Forms.MouseEventArgs e)
> {
> this.lblSource.DoDragDrop(this.lblSource.Text, DragDropEffects.Copy);
> }
>
> private void txtSource_MouseMove(object sender,
> System.Windows.Forms.MouseEventArgs e)
> {
> this.txtSource.DoDragDrop(this.txtSource.Text, DragDropEffects.Copy);
> }
>
> private void button1_Click(object sender, System.EventArgs e)
> {
> throw new ApplicationException("this an exception");
> }
> }
> }
>
>
>
> "Ignacio Machin ( .NET/ C#  MVP )" wrote:
>
> > Hi Ron,
> >
> >  Weird, it should throw an exception, unless that somewhere there is a
catch
> > {} eating the exceptions, if so it would be a surprise for me.
> >  Do this:
> >  Put a break point in the event handler, probably what is happening is
that
> > it's not being called, if not post the code here so we can exec. it
> >
> > Cheers,
> >
> > -- 
> > Ignacio Machin,
> > ignacio.machin AT dot.state.fl.us
> > Florida Department Of Transportation
> >
> > "Ron Green" <Ron Green@discussions.microsoft.com> wrote in message
> > news:6CDA21E0-BC6C-42C9-872A-60195F91A3EF@microsoft.com...
> > > Simple example:
> > > Winform with three controls: label, textbox, button.
> > >
> > > Create DragDrop event handler for label. Enter text in textbox and
drag it
> > > onto label. Works, no problem.
> > >
> > > remove code from dragdrop event handler and replace it with:
> > >
> > > throw new ApplicationException("This is an exception");
> > >
> > > Copy this line into the button click event handler also. Run the app.
> > > Press the button and you get a message that you have thrown an
unhandled
> > > excepton.
> > >
> > > Try the drag and drop. Nothing happens.
> > >
> > > Why does the button click produce an unhandled exception message and
> > > dragdrop does not?
> >
> >
> >