mcs/class/System/System.Diagnostics/Switch.cs

   1 //
   2 // System.Diagnostics.Switch.cs
   3 //
   4 // Comments from John R. Hicks <angryjohn69@nc.rr.com> original implementation
   5 // can be found at: /mcs/docs/apidocs/xml/en/System.Diagnostics
   6 //
   7 // Author:
   8 //      John R. Hicks  (angryjohn69@nc.rr.com)
   9 //      Jonathan Pryor (jonpryor@vt.edu)
  10 //
  11 // (C) 2001-2002
  12 //
  13
  14 using System.Collections;
  15
  16 namespace System.Diagnostics
  17 {
  18         public abstract class Switch
  19         {
  20                 private string name = "";
  21                 private string description = "";
  22                 private int switchSetting = 0;
  23
  24                 // MS Behavior is that (quoting from MSDN for OnSwitchSettingChanged()):
  25                 //              "...It is invoked the first time a switch reads its value from the
  26                 //              configuration file..."
  27                 // The docs + testing implies two things:
  28                 //      1. The value of the switch is not read in from the constructor
  29                 //      2. The value is instead read in on the first time get_SwitchSetting is
  30                 //              invoked
  31                 // Assuming that OnSwitchSettingChanged() is invoked on a .config file
  32                 // read and on all changes
  33                 //
  34                 // Thus, we need to keep track of whether or not switchSetting has been
  35                 // initialized.  Using `switchSetting=-1' seems logical, but if someone
  36                 // actually wants to use -1 as a switch value that would cause problems.
  37                 private bool initialized = false;
  38
  39                 protected Switch(string displayName, string description)
  40                 {
  41                         this.name = displayName;
  42                         this.description = description;
  43                 }
  44
  45                 public string Description {
  46                         get {return description;}
  47                 }
  48
  49                 public string DisplayName {
  50                         get {return name;}
  51                 }
  52
  53                 protected int SwitchSetting {
  54                         get {
  55                                 if (!initialized) {
  56                                         initialized = true;
  57                                         GetConfigFileSetting ();
  58                                         OnSwitchSettingChanged ();
  59                                 }
  60                                 return switchSetting;
  61                         }
  62                         set {
  63                                 if(switchSetting != value) {
  64                                         switchSetting = value;
  65                                         OnSwitchSettingChanged();
  66                                 }
  67                                 initialized = true;
  68                         }
  69                 }
  70
  71                 private void GetConfigFileSetting ()
  72                 {
  73                         // Load up the specified switch
  74                         IDictionary d =
  75                                 (IDictionary) DiagnosticsConfiguration.Settings ["switches"];
  76                         if (d != null) {
  77                                 object o = d [name];
  78         try {
  79           switchSetting = int.Parse (o.ToString());
  80         }
  81         catch {
  82           switchSetting = 0;
  83         }
  84                         }
  85                 }
  86
  87                 protected virtual void OnSwitchSettingChanged()
  88                 {
  89                         // Do nothing.  This is merely provided for derived classes to know when
  90                         // the value of SwitchSetting has changed.
  91                 }
  92         }
  93 }
  94