How can I get the current Trace Switch programatically?

问题

In my web.config I have:

<system.diagnostics>
  <switches>
    <add name="logLevelSwitch" value="1" />
  </switches>
</system.diagnostics>

Is there a way that I could call, for example:

System.Diagnostics.TraceSwitch["logLevelSwitch"]to get the current value?

回答1:

Once you've defined the switch value in your web.config file, it's easy to get this value from your application by creating a TraceSwitch with the same name:

private static TraceSwitch logSwitch = new TraceSwitch("logLevelSwitch",
    "This is your logLevelSwitch in the config file");

public static void Main(string[] args)
{
    // you can get its properties value then:
    Console.WriteLine("Trace switch {0} is configured as {1}",
        logSwitch.DisplayName,
        logSwitch.Level.ToString());

    // and you can use it like this:
    if (logSwitch.TraceError)
        Trace.WriteLine("This is an error");

    // or like this also:
    Trace.WriteLineIf(logSwitch.TraceWarning, "This is a warning");
}

Moreover, for this to work, according to the documentation:

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 enabledebugging 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.

来源：https://stackoverflow.com/questions/13108577/how-can-i-get-the-current-trace-switch-programatically