I'm practicing for the C# brain bench test by reviewing how delegates work.
(Delegates are easy to to with visual studio because you normally use the
delegates that some API as already defined. I'm worried they are going to
make me do my own delegates from scratch.) I see that line 33 of
Default.aspx is indeed executing when I single step with the debugger. As
you can see (on lines of 17 and 18 of propertyDemo.cs I have set up a
delegate and I'm single stepping thu this too). But why do not the contents
'"old=abc" new="xyz"'show up in the list box I have set up? It is clearly
being added when I single step with the debugger.
I have set up session state and when that did not work I set up ViewState
and that did not help either!
File Default.aspx:
<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dt d">
<script runat="server">
PropertyDemo pd;
/*005*/ protected void Clear_Click(obj ect sender, EventArgs e) {
/*006*/ tbValue.Text = "";
/*007*/ }
/*008*/ protected void PropertyDemo_Cl ick(object sender, EventArgs e){
/*009*/ pd.name = tbValue.Text;
/*010*/ }
/*011*/ protected void Page_Init(objec t sender, EventArgs e){
/*012*/ pd = new PropertyDemo();
/*013*/ pd.m_eventNameC hange += new
PropertyDemo.Na meChangeEvent(p d_m_eventNameCh ange);
/*014*/ lbLog.Items.Add ("init");
/*015*/ }
/*016*/ protected void Page_Load(objec t sender, EventArgs e){
/*017*/ lbLog.Items.Add ("load");
/*018*/ pd = (PropertyDemo)S ession["pd"];
/*019*/ if (pd == null){
/*020*/ pd = new PropertyDemo();
/*021*/ pd.m_eventNameC hange += new
PropertyDemo.Na meChangeEvent(p d_m_eventNameCh ange);
/*022*/ }
/*023*/ ArrayList litems = (ArrayList)Sess ion["log"];
/*024*/ if (litems != null)
/*025*/ foreach (object o in litems)
/*026*/ lbLog.Items.Add (""+o);
/*027*/ litems = (ArrayList)View State["log"];
/*028*/ if (litems != null)
/*029*/ foreach (object o in litems)
/*030*/ lbLog.Items.Add (""+o);
/*031*/ }
/*032*/ void pd_m_eventNameC hange(string sOld, string sNew){
/*033*/ lbLog.Items.Add ("old=" + sOld + " new=" + sNew);
/*034*/ SaveState();
/*035*/ }
/*036*/ protected void Page_Unload(obj ect sender, EventArgs e){
/*037*/ SaveState();
/*038*/ }
/*039*/ private void SaveState(){
/*040*/ lbLog.Items.Add ("page unload");
/*041*/ Session["pd"] = pd;
/*042*/ ArrayList log = new ArrayList();
/*043*/ foreach (object o in lbLog.Items){
/*044*/ log.Add(o);
/*045*/ }
/*046*/ Session["log"] = log;
/*047*/ ArrayList log2 = (ArrayList)Sess ion["log"];
/*048*/ ViewState["log"] = log;
/*049*/ }
/*050*/ protected void Set_Click(objec t sender, EventArgs e){
/*051*/ pd.name = tbValue.Text;
/*052*/ }
/*053*/ protected void getter_Click(ob ject sender, EventArgs e){
/*054*/ tbValue.Text = pd.name;
/*055*/ }
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Demonstr ate Getters and Setters and Delegates</title>
</head>
<body>
<form id="form1" runat="server">
<table border="1" style="width: 40px; height: 38px">
<tbody>
<tr>
<td><asp:Butt on ID="setter" runat="server" Text="set"
OnClick="Set_Cl ick" /></td>
<td>
<asp:Button ID="getter" runat="server" Text="get"
OnClick="getter _Click" /></td>
<td><asp:Butt on ID="clearer" runat="server" Text="Clear"
OnClick="Clear_ Click" /></td>
<td>
<asp:TextBox ID="tbValue" runat="server"> </asp:TextBox></td>
</tr>
<tr><td colspan="4"><as p:ListBox ID="lbLog" runat="server"
Width="278px" Height="736px"> </asp:ListBox></td></tr>
</tbody>
</table>
</form>
</body>
</html>
File PropertyDemo.cs
/*001*/ using System;
/*002*/ using System.Data;
/*003*/ using System.Configur ation;
/*004*/ using System.Web;
/*005*/ using System.Web.Secu rity;
/*006*/ using System.Web.UI;
/*007*/ using System.Web.UI.W ebControls;
/*008*/ using System.Web.UI.W ebControls.WebP arts;
/*009*/ using System.Web.UI.H tmlControls;
/*010*/
/*011*/ /// <summary>
/*012*/ /// Summary description for PropertyDemo
/*013*/ /// </summary>
/*014*/ public class PropertyDemo
/*015*/ {
/*016*/ private string m_sName;
/*017*/ public delegate void NameChangeEvent (String sOld, String sNew);
/*018*/ public PropertyDemo()
/*019*/ {
/*020*/ }
/*021*/ public string name
/*022*/ {
/*023*/ get {
/*024*/ this.m_eventNam eChange(m_sName ,"");
/*025*/ return m_sName;
/*026*/ }
/*027*/ set {
/*028*/ this.m_eventNam eChange(m_sName , value);
/*029*/ m_sName = value;
/*030*/ }
/*031*/ }
/*032*/ }
/*033*/
