I'm trying to create a ComboBox class that will present the same printout
options to users no matter where I need to use the combo box. I extend the
ComboBox class and in the constructor I add predefined print destinations,
along with setting other properties.

The problem comes when I drop the class onto the form in the designer. The
code thats gets generated automatically "scrapes" the constructor and
creates an AddRange() call for the values I use during instantiation.

This behavior is annoying. When I run the program two sets of options
appear in the drop down. On top of the AddRange() call being injected, the
values for the AddRange() call are converted from variable references to
literal values. If I use the combo box throughout my application and then
decide to change the values of the variables, I'll have to search and
replace the literal values, instead of changing the values in the class.

Here is a sample. I used sharpDevelop, but the problem(?) occurs in
devStudio, also.

using System;
using System.Drawing;
using System.Windows.Forms;


namespace WinFormsTest {
public class MainForm : System.Windows.Forms.Form {
public MainForm() {
InitializeComponent();
}
[STAThread]
public static void Main(string[] args) {
Application.Run(new MainForm());
}
private void InitializeComponent() {
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(292, 271);
this.Name = "MainForm";
}
}


public class PrintComboBox : System.Windows.Forms.ComboBox {
public PrintComboBox() {
Items.Add( DEST_SCREEN );
Items.Add( DEST_FILE );
Items.Add( DEST_EMAIL );
DropDownStyle = ComboBoxStyle.DropDownList;
SelectedIndex = 0;
}
private const String DEST_SCREEN = "View";
private const String DEST_FILE = "File";
private const String DEST_EMAIL = "eMail";
}



}


When you switch to design mode, the PrintComboBox will appear in the Custom
Components section of the toolbox. Add the combo box to the form, then
check the source code and you'll see this statement will have been added to
MainForm.InitializeComponent().

this.printComboBox1.Items.AddRange(new object[] {
"View",
"File",
"eMail"});


There must be some explanation, since both devStudio and sharpDevelop
produce the same results.
Is this typical behaviour?

Am I implementing this correctly?


Thanks,
Mark

You may want to try adding:

[ DesignerSerializationVisibility(DesignerSerializat ionVisibility.Hidden) ]

To your Items property.

You can also add a ShouldSerializeItems method to your class that always
returns false.

--
Francisco Padron
www.chartfx.com


"MLongmire" <mark (AT) mlongmire (DOT) net> wrote