ILogger Interface
 

Defines an MSBuild logger, which subscribes to build system events.

MSBuild is now included in Visual Studio instead of the .NET Framework. You can use MSBuild 12.0 side-by-side with versions previously deployed with the .NET Framework.For more information, see What's New in MSBuild 12.0.

Namespace:   Microsoft.Build.Framework
Assembly:  Microsoft.Build.Framework (in Microsoft.Build.Framework.dll)

[ComVisibleAttribute(true)]
public interface ILogger
[ComVisibleAttribute(true)]
public interface class ILogger
[<ComVisibleAttribute(true)>]
type ILogger = interface end
<ComVisibleAttribute(True)>
Public Interface ILogger
NameDescription
System_CAPS_pubproperty

Gets or sets the user-defined parameters of the logger.

MSBuild is now included in Visual Studio instead of the .NET Framework. You can use MSBuild 12.0 side-by-side with versions previously deployed with the .NET Framework.For more information, see What's New in MSBuild 12.0.

System_CAPS_pubproperty

Gets or sets the level of detail to show in the event log.

MSBuild is now included in Visual Studio instead of the .NET Framework. You can use MSBuild 12.0 side-by-side with versions previously deployed with the .NET Framework.For more information, see What's New in MSBuild 12.0.

NameDescription
System_CAPS_pubmethod Initialize

Subscribes loggers to specific events. This method is called when the logger is registered with the build engine, before any events are raised.

MSBuild is now included in Visual Studio instead of the .NET Framework. You can use MSBuild 12.0 side-by-side with versions previously deployed with the .NET Framework.For more information, see What's New in MSBuild 12.0.

System_CAPS_pubmethod Shutdown

Releases the resources allocated to the logger at the time of initialization or during the build. This method is called when the logger is unregistered from the engine, after all events are raised. A host of MSBuild typically unregisters loggers immediately before quitting.

MSBuild is now included in Visual Studio instead of the .NET Framework. You can use MSBuild 12.0 side-by-side with versions previously deployed with the .NET Framework.For more information, see What's New in MSBuild 12.0.

All logger classes must implement this interface to be recognized by the MSBuild engine.

Instead of implementing this interface directly, you can also derive your class from the helper class, Logger, which provides default implementations of some ILogger members.

The following example shows how to write a basic logger.

using System;
using System.IO;
using System.Security;
using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;

namespace MyLoggers
{
	// This logger will derive from the Microsoft.Build.Utilities.Logger class,
	// which provides it with getters and setters for Verbosity and Parameters,
	// and a default empty Shutdown() implementation.
	public class BasicFileLogger : Logger
	{
		/// <summary>
		/// Initialize is guaranteed to be called by MSBuild at the start of the build
		/// before any events are raised.
		/// </summary>
		public override void Initialize(IEventSource eventSource)
		{
			// The name of the log file should be passed as the first item in the
			// "parameters" specification in the /logger switch.  It is required
			// to pass a log file to this logger. Other loggers may have zero or more than 
			// one parameters.
			if (null == Parameters)
			{
				throw new LoggerException("Log file was not set.");
			}
			string[] parameters = Parameters.Split(';');

			string logFile = parameters[0];
			if (String.IsNullOrEmpty(logFile))
			{
				throw new LoggerException("Log file was not set.");
			}

			if (parameters.Length > 1)
			{
				throw new LoggerException("Too many parameters passed.");
			}

			try
			{
				// Open the file
				this.streamWriter = new StreamWriter(logFile);
			}
			catch (Exception ex)
			{
				if
				(
					ex is UnauthorizedAccessException
					|| ex is ArgumentNullException
					|| ex is PathTooLongException
					|| ex is DirectoryNotFoundException
					|| ex is NotSupportedException
					|| ex is ArgumentException
					|| ex is SecurityException
					|| ex is IOException
				)
				{
					throw new LoggerException("Failed to create log file: " + ex.Message);
				}
				else
				{
					// Unexpected failure
					throw;
				}
			}

			// For brevity, we'll only register for certain event types. Loggers can also
			// register to handle TargetStarted/Finished and other events.
			eventSource.ProjectStarted += new ProjectStartedEventHandler(eventSource_ProjectStarted);
			eventSource.TaskStarted += new TaskStartedEventHandler(eventSource_TaskStarted);
			eventSource.MessageRaised += new BuildMessageEventHandler(eventSource_MessageRaised);
			eventSource.WarningRaised += new BuildWarningEventHandler(eventSource_WarningRaised);
			eventSource.ErrorRaised += new BuildErrorEventHandler(eventSource_ErrorRaised);
			eventSource.ProjectFinished += new ProjectFinishedEventHandler(eventSource_ProjectFinished);
		}

		void eventSource_ErrorRaised(object sender, BuildErrorEventArgs e)
		{
			// BuildErrorEventArgs adds LineNumber, ColumnNumber, File, amongst other parameters
			string line = String.Format(": ERROR {0}({1},{2}): ", e.File, e.LineNumber, e.ColumnNumber);
			WriteLineWithSenderAndMessage(line, e);
		}

		void eventSource_WarningRaised(object sender, BuildWarningEventArgs e)
		{
			// BuildWarningEventArgs adds LineNumber, ColumnNumber, File, amongst other parameters
			string line = String.Format(": Warning {0}({1},{2}): ", e.File, e.LineNumber, e.ColumnNumber);
			WriteLineWithSenderAndMessage(line, e);
		}

		void eventSource_MessageRaised(object sender, BuildMessageEventArgs e)
		{
			// BuildMessageEventArgs adds Importance to BuildEventArgs
			// Let's take account of the verbosity setting we've been passed in deciding whether to log the message
			if ((e.Importance == MessageImportance.High && IsVerbosityAtLeast(LoggerVerbosity.Minimal))
				|| (e.Importance == MessageImportance.Normal && IsVerbosityAtLeast(LoggerVerbosity.Normal))
				|| (e.Importance == MessageImportance.Low && IsVerbosityAtLeast(LoggerVerbosity.Detailed))				
				)
			{
				WriteLineWithSenderAndMessage(String.Empty, e);
			}
		}

		void eventSource_TaskStarted(object sender, TaskStartedEventArgs e)
		{
			// TaskStartedEventArgs adds ProjectFile, TaskFile, TaskName
			// To keep this log clean, this logger will ignore these events.
		}

		void eventSource_ProjectStarted(object sender, ProjectStartedEventArgs e)
		{
			// ProjectStartedEventArgs adds ProjectFile, TargetNames
			// Just the regular message string is good enough here, so just display that.
			WriteLine(String.Empty, e);
			indent++;
		}

		void eventSource_ProjectFinished(object sender, ProjectFinishedEventArgs e)
		{
			// The regular message string is good enough here too.
			indent--;
			WriteLine(String.Empty, e);
		}

		/// <summary>
		/// Write a line to the log, adding the SenderName and Message
		/// (these parameters are on all MSBuild event argument objects)
		/// </summary>
		private void WriteLineWithSenderAndMessage(string line, BuildEventArgs e)
		{
			if (0 == String.Compare(e.SenderName, "MSBuild", true /*ignore case*/))
			{
				// Well, if the sender name is MSBuild, let's leave it out for prettiness
				WriteLine(line, e);
			}
			else
			{
				WriteLine(e.SenderName + ": " + line, e);
			}
		}

		/// <summary>
		/// Just write a line to the log
		/// </summary>
		private void WriteLine(string line, BuildEventArgs e)
		{
			for (int i = indent; i > 0; i--)
			{
				streamWriter.Write("\t");
			}
			streamWriter.WriteLine(line + e.Message);
		}

		/// <summary>
		/// Shutdown() is guaranteed to be called by MSBuild at the end of the build, after all 
		/// events have been raised.
		/// </summary>
		public override void Shutdown()
		{
			// Done logging, let go of the file
			streamWriter.Close();
		}

		private StreamWriter streamWriter;
		private int indent;
	}
}
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