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 using System.Collections.Specialized;
  37 #if CONFIGURATION_DEP
  38 using System.Configuration;
  39 #endif
  40
  41 namespace System.Diagnostics
  42 {
  43         public abstract class Switch
  44         {
  45                 private string name;
  46                 private string description;
  47                 private int switchSetting;
  48                 private string value;
  49                 private string defaultSwitchValue;
  50                 // MS Behavior is that (quoting from MSDN for OnSwitchSettingChanged()):
  51                 //              "...It is invoked the first time a switch reads its value from the
  52                 //              configuration file..."
  53                 // The docs + testing implies two things:
  54                 //      1. The value of the switch is not read in from the constructor
  55                 //      2. The value is instead read in on the first time get_SwitchSetting is
  56                 //              invoked
  57                 // Assuming that OnSwitchSettingChanged() is invoked on a .config file
  58                 // read and on all changes
  59                 //
  60                 // Thus, we need to keep track of whether or not switchSetting has been
  61                 // initialized.  Using `switchSetting=-1' seems logical, but if someone
  62                 // actually wants to use -1 as a switch value that would cause problems.
  63                 private bool initialized;
  64
  65                 protected Switch(string displayName, string description)
  66                 {
  67                         this.name = displayName;
  68                         this.description = description;
  69                 }
  70
  71                 protected Switch(string displayName, string description, string defaultSwitchValue)
  72                         : this (displayName, description)
  73                 {
  74                         this.defaultSwitchValue = defaultSwitchValue;
  75                 }
  76
  77                 public string Description {
  78                         get {return description;}
  79                 }
  80
  81                 public string DisplayName {
  82                         get {return name;}
  83                 }
  84
  85                 protected int SwitchSetting {
  86                         get {
  87                                 if (!initialized) {
  88                                         initialized = true;
  89                                         GetConfigFileSetting ();
  90                                         OnSwitchSettingChanged ();
  91                                 }
  92                                 return switchSetting;
  93                         }
  94                         set {
  95                                 if(switchSetting != value) {
  96                                         switchSetting = value;
  97                                         OnSwitchSettingChanged();
  98                                 }
  99                                 initialized = true;
 100                         }
 101                 }
 102
 103                 StringDictionary attributes = new StringDictionary ();
 104
 105 #if XML_DEP
 106                 [System.Xml.Serialization.XmlIgnore]
 107 #endif
 108                 public StringDictionary Attributes {
 109                         get { return attributes; }
 110                 }
 111
 112                 protected string Value {
 113                         get { return value; }
 114                         set {
 115                                 this.value = value;
 116 #if CONFIGURATION_DEP
 117                                 try {
 118                                         OnValueChanged ();
 119                                 } catch (Exception ex) {
 120                                         string msg = string.Format ("The config "
 121                                                 + "value for Switch '{0}' was "
 122                                                 + "invalid.", DisplayName);
 123
 124                                         throw new ConfigurationErrorsException (
 125                                                 msg, ex);
 126                                 }
 127 #else
 128                                 OnValueChanged ();
 129 #endif
 130                         }
 131                 }
 132
 133                 protected internal virtual string [] GetSupportedAttributes ()
 134                 {
 135                         return null;
 136                 }
 137
 138                 protected virtual void OnValueChanged ()
 139                 {
 140                 }
 141
 142                 private void GetConfigFileSetting ()
 143                 {
 144                         IDictionary d = (IDictionary) DiagnosticsConfiguration.Settings ["switches"];
 145
 146                         // Load up the specified switch
 147                         if (d != null) {
 148                                 if (d.Contains (name)) {
 149 #if CONFIGURATION_DEP
 150                                         Value = d [name] as string;
 151 #else
 152                                         switchSetting = (int) d [name];
 153 #endif
 154                                         return;
 155                                 }
 156                         }
 157
 158                         if (defaultSwitchValue != null) {
 159                                 value = defaultSwitchValue;
 160                                 OnValueChanged ();
 161                         }
 162                 }
 163
 164                 protected virtual void OnSwitchSettingChanged()
 165                 {
 166                         // Do nothing.  This is merely provided for derived classes to know when
 167                         // the value of SwitchSetting has changed.
 168                 }
 169         }
 170 }