Switch Class
 

Provides an abstract base class to create new debugging and tracing switches.

Namespace:   System.Diagnostics
Assembly:  System (in System.dll)


Syntax
public abstract class Switch
public ref class Switch abstract 
[<AbstractClass>]
type Switch = class end
Public MustInherit Class Switch
Constructors
NameDescription
System_CAPS_protmethod Switch

Initializes a new instance of the Switch class.

System_CAPS_protmethod Switch

Initializes a new instance of the Switch class, specifying the display name, description, and default value for the switch.

Properties
NameDescription
System_CAPS_pubproperty

Gets the custom switch attributes defined in the application configuration file.

System_CAPS_pubproperty

Gets a description of the switch.

System_CAPS_pubproperty

Gets a name used to identify the switch.

System_CAPS_protproperty

Gets or sets the current setting for this switch.

System_CAPS_protproperty

Gets or sets the value of the switch.

Methods
NameDescription
System_CAPS_pubmethod Equals

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethod Finalize

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethod GetHashCode

Serves as the default hash function. (Inherited from Object.)

System_CAPS_protmethod GetSupportedAttributes

Gets the custom attributes supported by the switch.

System_CAPS_pubmethod GetType

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_protmethod MemberwiseClone

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_protmethod OnSwitchSettingChanged

Invoked when the property is changed.

System_CAPS_protmethod OnValueChanged

Invoked when the property is changed.

System_CAPS_pubmethod ToString

Returns a string that represents the current object.(Inherited from Object.)

Remarks

A switch provides an efficient mechanism for controlling tracing and debugging output at run time using external settings. The Switch class implements default behavior for switches, allowing you to change the switch level at run time.

This class is the base class for the BooleanSwitch, SourceSwitch and the TraceSwitch classes. These switches meet most debugging and tracing needs. For more information about trace switches, see Trace Switches.

You must enable tracing or debugging to use a switch. The following syntax is compiler specific. If you use compilers other than C# or Visual Basic, refer to the documentation for your compiler.

  • To enable debugging in C#, add the /d:DEBUG flag to the compiler command line when you compile your code, or you can add #define DEBUG to the top of your file. In Visual Basic, add the /d:DEBUG=True flag to the compiler command line.

  • To enable tracing using in C#, add the /d:TRACE flag to the compiler command line when you compile your code, or add #define TRACE to the top of your file. In Visual Basic, add the /d:TRACE=True flag to the compiler command line.

To set the level of your switch, edit the configuration file that corresponds to the name of your application. Within this file, you can add a switch and set its value, remove a switch, or clear all the switches previously set by the application. The configuration file should be formatted like the following example:

<configuration>
  <system.diagnostics>
    <switches>
      <add name="mySwitch" value="true" />
    </switches>
  </system.diagnostics>
</configuration>

This example configuration section defines a BooleanSwitch with the property set to mySwitch and the value set to true. Within your application, you can use the configured switch value by creating a BooleanSwitch with the same name, as shown in the following code example.

private static BooleanSwitch boolSwitch = new BooleanSwitch("mySwitch",
    "Switch in config file");

public static void Main( )
{
    //...
    Console.WriteLine("Boolean switch {0} configured as {1}",
        boolSwitch.DisplayName, boolSwitch.Enabled.ToString());
    if (boolSwitch.Enabled)
    {
        //...
    }
}
private:
    static BooleanSwitch^ boolSwitch = gcnew BooleanSwitch("mySwitch",
        "Switch in config file");

public:
    static void Main( )
    {
        //...
        Console::WriteLine("Boolean switch {0} configured as {1}",
            boolSwitch->DisplayName, ((Boolean^)boolSwitch->Enabled)->ToString());
        if (boolSwitch->Enabled)
        {
            //...
        }
    }

Notes to Inheritors:

If you need trace levels, or mechanisms for setting switch levels different from those provided by BooleanSwitch, SourceSwitch and TraceSwitch, you can inherit from Switch. When inheriting from this class, you must implement the method.

Examples

The following example shows how to define a new Switch class with four levels of tracing that can be used to trace a call stack. You can use the switch to instrument your application to log each time the method is entered or exited.

The first example creates the enumeration used to set the level of the switch.

// The following are possible values for the new switch.
public enum MethodTracingSwitchLevel
{
    Off = 0,
    EnteringMethod = 1,
    ExitingMethod = 2,
    Both = 3,
}
' The following are possible values for the new switch.
Public Enum MethodTracingSwitchLevel
    Off = 0
    EnteringMethod = 1
    ExitingMethod = 2
    Both = 3
End Enum 'MethodTracingSwitchLevel
// The following are possible values for the new switch.
public enum class MethodTracingSwitchLevel
{
    Off = 0,
    EnteringMethod = 1,
    ExitingMethod = 2,
    Both = 3
};

The following example creates the new switch. The code implements a Level property to set the value of the new switch. Level calls the protected property that assigns the value to the new switch. This example also implements two assessor properties to get the assigned value of the switch.

public class MyMethodTracingSwitch : Switch
{
     protected bool outExit;
     protected bool outEnter;
     protected MethodTracingSwitchLevel level;

     public MyMethodTracingSwitch(string displayName, string description) :
         base(displayName, description)
     {
     }

     public MethodTracingSwitchLevel Level
     {
         get
         {
             return level;
         }
         set
         {
             SetSwitchSetting((int)value);
         }
     }

     protected void SetSwitchSetting(int value)
     {
         if (value < 0)
         {
             value = 0;
         }
         if (value > 3)
         {
             value = 3;
         }

         level = (MethodTracingSwitchLevel)value;

         outEnter = false;
         if ((value == (int)MethodTracingSwitchLevel.EnteringMethod) ||
             (value == (int)MethodTracingSwitchLevel.Both))
         {
             outEnter = true;
         }

         outExit = false;
         if ((value == (int)MethodTracingSwitchLevel.ExitingMethod) ||
             (value == (int)MethodTracingSwitchLevel.Both))
         {
             outExit = true;
         }
     }

     public bool OutputExit
     {
         get
         {
             return outExit;
         }
     }

     public bool OutputEnter
     {
         get
         {
             return outEnter;
         }
     }
 }
Public Class MyMethodTracingSwitch
    Inherits Switch
    Protected outExit As Boolean
    Protected outEnter As Boolean
    Protected myLevel As MethodTracingSwitchLevel

    Public Sub New(displayName As String, description As String)
        MyBase.New(displayName, description)
    End Sub 'NewNew


    Public Property Level() As MethodTracingSwitchLevel
        Get
            Return myLevel
        End Get
        Set
            SetSwitchSetting(CInt(value))
        End Set
    End Property


    Protected Sub SetSwitchSetting(value As Integer)
        If value < 0 Then
            value = 0
        End If
        If value > 3 Then
            value = 3
        End If

        myLevel = CType(value, MethodTracingSwitchLevel)

        outEnter = False
        If value = CInt(MethodTracingSwitchLevel.EnteringMethod) Or _
            value = CInt(MethodTracingSwitchLevel.Both) Then

            outEnter = True
        End If

        outExit = False
        If value = CInt(MethodTracingSwitchLevel.ExitingMethod) Or _
            value = CInt(MethodTracingSwitchLevel.Both) Then

            outExit = True
        End If
    End Sub 'SetSwitchSetting


    Public ReadOnly Property OutputExit() As Boolean
        Get
            Return outExit
        End Get
    End Property


    Public ReadOnly Property OutputEnter() As Boolean
        Get
            Return outEnter
        End Get
    End Property
End Class 'MyMethodTracingSwitch
public ref class MyMethodTracingSwitch: public Switch
{
protected:
    bool outExit;
    bool outEnter;
    MethodTracingSwitchLevel level;

public:
    MyMethodTracingSwitch( String^ displayName, String^ description )
       : Switch( displayName, description )
    {}

    property MethodTracingSwitchLevel Level
    {
        MethodTracingSwitchLevel get()
        {
            return level;
        }

       void set( MethodTracingSwitchLevel value )
       {
           SetSwitchSetting( (int)value );
       }
    }

protected:
    void SetSwitchSetting( int value )
    {
        if ( value < 0 )
        {
            value = 0;
        }

        if ( value > 3 )
        {
            value = 3;
        }

        level = (MethodTracingSwitchLevel)value;
        outEnter = false;
        if ((value == (int)MethodTracingSwitchLevel::EnteringMethod) ||
            (value == (int)MethodTracingSwitchLevel::Both))
        {
            outEnter = true;
        }

        outExit = false;
        if ((value == (int)MethodTracingSwitchLevel::ExitingMethod) ||
            (value == (int)MethodTracingSwitchLevel::Both))
        {
            outExit = true;
        }
    }

public:
    property bool OutputExit
    {
        bool get()
        {
            return outExit;
        }
    }

    property bool OutputEnter
    {
        bool get()
        {
            return outEnter;
        }
    }
};

The following example creates a new switch in Main. It creates a new switch and assigns it a value. Then, depending on the switch settings, it outputs debugging messages for entering and leaving the method.

public class Class1
{
    /* Create an instance of MyMethodTracingSwitch.*/
    static MyMethodTracingSwitch mySwitch =
        new MyMethodTracingSwitch("Methods", "Trace entering and exiting method");

    public static void Main()
    {
        // Add the console listener to see trace messages as console output
        Trace.Listeners.Add(new ConsoleTraceListener(true));
        Debug.AutoFlush = true;

        // Set the switch level to both enter and exit
        mySwitch.Level = MethodTracingSwitchLevel.Both;

        // Write a diagnostic message if the switch is set to entering.
        Debug.WriteLineIf(mySwitch.OutputEnter, "Entering Main");

        // Insert code to handle processing here...

        // Write another diagnostic message if the switch is set to exiting.
        Debug.WriteLineIf(mySwitch.OutputExit, "Exiting Main");
    }
}
Public Class Class1
    ' Create an instance of MyMethodTracingSwitch.
    Private Shared mySwitch As New _
        MyMethodTracingSwitch("Methods", "Trace entering and exiting method")

    Public Shared Sub Main()
        ' Add the console listener to see trace messages as console output
        Trace.Listeners.Add(New ConsoleTraceListener(True))
        Debug.AutoFlush = True

        ' Set the switch level to both enter and exit
        mySwitch.Level = MethodTracingSwitchLevel.Both

        ' Write a diagnostic message if the switch is set to entering.
        Debug.WriteLineIf(mySwitch.OutputEnter, "Entering Main")

        ' Insert code to handle processing here...

        ' Write another diagnostic message if the switch is set to exiting.
        Debug.WriteLineIf(mySwitch.OutputExit, "Exiting Main")
    End Sub
End Class 'MyClass
public ref class Class1
{
private:

    /* Create an instance of MyMethodTracingSwitch.*/
    static MyMethodTracingSwitch^ mySwitch =
        gcnew MyMethodTracingSwitch( "Methods","Trace entering and exiting method" );

public:
    static void main()
    {
        // Add the console listener to see trace messages as console output
        Trace::Listeners->Add(gcnew ConsoleTraceListener(true));
        Debug::AutoFlush = true;

        // Set the switch level to both enter and exit
        mySwitch->Level = MethodTracingSwitchLevel::Both;

        // Write a diagnostic message if the switch is set to entering.
        Debug::WriteLineIf(mySwitch->OutputEnter, "Entering Main");

        // Insert code to handle processing here...

        // Write another diagnostic message if the switch is set to exiting.
        Debug::WriteLineIf(mySwitch->OutputExit, "Exiting Main");
    }
};
Version Information
Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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