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 //
  15 // Permission is hereby granted, free of charge, to any person obtaining
  16 // a copy of this software and associated documentation files (the
  17 // "Software"), to deal in the Software without restriction, including
  18 // without limitation the rights to use, copy, modify, merge, publish,
  19 // distribute, sublicense, and/or sell copies of the Software, and to
  20 // permit persons to whom the Software is furnished to do so, subject to
  21 // the following conditions:
  22 //
  23 // The above copyright notice and this permission notice shall be
  24 // included in all copies or substantial portions of the Software.
  25 //
  26 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  27 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  28 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  29 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  30 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  31 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  32 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  33 //
  34
  35 using System.Collections;
  36
  37 namespace System.Diagnostics
  38 {
  39         public abstract class Switch
  40         {
  41                 private string name = "";
  42                 private string description = "";
  43                 private int switchSetting = 0;
  44
  45                 // MS Behavior is that (quoting from MSDN for OnSwitchSettingChanged()):
  46                 //              "...It is invoked the first time a switch reads its value from the
  47                 //              configuration file..."
  48                 // The docs + testing implies two things:
  49                 //      1. The value of the switch is not read in from the constructor
  50                 //      2. The value is instead read in on the first time get_SwitchSetting is
  51                 //              invoked
  52                 // Assuming that OnSwitchSettingChanged() is invoked on a .config file
  53                 // read and on all changes
  54                 //
  55                 // Thus, we need to keep track of whether or not switchSetting has been
  56                 // initialized.  Using `switchSetting=-1' seems logical, but if someone
  57                 // actually wants to use -1 as a switch value that would cause problems.
  58                 private bool initialized = false;
  59
  60                 protected Switch(string displayName, string description)
  61                 {
  62                         this.name = displayName;
  63                         this.description = description;
  64                 }
  65
  66                 public string Description {
  67                         get {return description;}
  68                 }
  69
  70                 public string DisplayName {
  71                         get {return name;}
  72                 }
  73
  74                 protected int SwitchSetting {
  75                         get {
  76                                 if (!initialized) {
  77                                         initialized = true;
  78                                         GetConfigFileSetting ();
  79                                         OnSwitchSettingChanged ();
  80                                 }
  81                                 return switchSetting;
  82                         }
  83                         set {
  84                                 if(switchSetting != value) {
  85                                         switchSetting = value;
  86                                         OnSwitchSettingChanged();
  87                                 }
  88                                 initialized = true;
  89                         }
  90                 }
  91
  92                 private void GetConfigFileSetting ()
  93                 {
  94                         try {
  95
  96                                 // Load up the specified switch
  97                                 IDictionary d = (IDictionary) DiagnosticsConfiguration.Settings ["switches"];
  98                                 if (d != null)
  99                                         switchSetting = int.Parse (d [name].ToString());
 100                         } catch {
 101                                 switchSetting = 0;
 102                         }
 103                 }
 104
 105                 protected virtual void OnSwitchSettingChanged()
 106                 {
 107                         // Do nothing.  This is merely provided for derived classes to know when
 108                         // the value of SwitchSetting has changed.
 109                 }
 110         }
 111 }
 112