C# in a Nutshell, Second Edition

Name

Trace

Synopsis

This class supplies static methods and properties to provide tracing ability. The calls to the Trace methods and properties are executed only if tracing is enabled. (See the introduction to this chapter for instructions on enabling tracing.)

The static properties allow you to adjust the settings that are used when you call the methods. You can specify that output be indented a certain amount with IndentLevel or increase or decrease the IndentLevel by one using Indent( ) and Unindent( ). You can also adjust the number of spaces each indent level adds using IndentSize. AutoFlush makes sure that after each use of a Trace method, the Listeners are flushed.

Write( ) and WriteLine( ) simply write to each TraceListener in the Listeners collection (by default, this collection includes an instance of DefaultTraceListener). WriteIf( ) and WriteLineIf( ) do the same, but only if the specified condition evaluates to true. Assert( ) emits an error message if a condition evaluates to false, and Fail( ) always emits an error message.

One possible point of confusion is that Listeners is read-only. This means that you may not point Listeners to a different collection. You can, however, add new TraceListener objects to the TraceListenerCollection with the TraceListenerCollection.Add( ) method.

You can use the application configuration file to configure this class. Under the <system.diagnostics> element, add a <trace> element. You can set attributes for this element that correspond ...