ITask Interface
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ITask Interface

 

Defines a task, which is a unit of executable code used by MSBuild to perform build operations.

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)

public interface ITask

NameDescription
System_CAPS_pubpropertyBuildEngine

Gets or sets the build engine associated with the task.

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_pubpropertyHostObject

Gets or sets any host object that is associated with the task.

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_pubmethodExecute()

Executes a task.

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 task classes must implement this interface to be recognized by the build engine. Instead of implenting this interface directly, you can also derive your class from the helper class, Task, which provides default implementations of some ITask members.

The following example shows the code from a complete task implementation.

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

namespace Microsoft.Build.Tasks
{
	/*
	 * Class: MakeDir
	 *
	 * An MSBuild task that creates one or more directories.
	 *
	 */
	public class MakeDir : Task
	{
	    // The Required attribute indicates the following to MSBuild:
	    //	     - if the parameter is a scalar type, and it is not supplied, fail the build immediately
	    //	     - if the parameter is an array type, and it is not supplied, pass in an empty array
	    // In this case the parameter is an array type, so if a project fails to pass in a value for the 
            // Directories parameter, the task will get invoked, but this implementation will do nothing,
            // because the array will be empty.
		[Required]
            // Directories to create.
		public ITaskItem[] Directories
		{
			get
			{
				return directories;
			}

			set
			{
				directories = value;
			}
		}

		// The Output attribute indicates to MSBuild that the value of this property can be gathered after the
		// task has returned from Execute(), if the project has an <Output> tag under this task's element for 
		// this property.
		[Output]
		// A project may need the subset of the inputs that were actually created, so make that available here.
		public ITaskItem[] DirectoriesCreated
		{
			get
			{
				return directoriesCreated;
			}
		}

		private ITaskItem[] directories;
		private ITaskItem[] directoriesCreated;

		/// <summary>
		/// Execute is part of the Microsoft.Build.Framework.ITask interface.
		/// When it's called, any input parameters have already been set on the task's properties.
		/// It returns true or false to indicate success or failure.
		/// </summary>
		public override bool Execute()
		{
			ArrayList items = new ArrayList();
			foreach (ITaskItem directory in Directories)
			{
				// ItemSpec holds the filename or path of an Item
				if (directory.ItemSpec.Length > 0)
				{
					try
					{
						// Only log a message if we actually need to create the folder
						if (!Directory.Exists(directory.ItemSpec))
						{
							Log.LogMessage(MessageImportance.Normal, "Creating directory " + directory.ItemSpec);
							Directory.CreateDirectory(directory.ItemSpec);
						}

						// Add to the list of created directories
						items.Add(directory);
					}
					// If a directory fails to get created, log an error, but proceed with the remaining 
					// directories.
					catch (Exception ex)
					{
						if (ex is IOException
							|| ex is UnauthorizedAccessException
							|| ex is PathTooLongException
							|| ex is DirectoryNotFoundException
							|| ex is SecurityException)
						{
							Log.LogError("Error trying to create directory " + directory.ItemSpec + ". " + ex.Message);
						}
						else
						{
							throw;
						}
					}
				}
			}

			// Populate the "DirectoriesCreated" output items.
			directoriesCreated = (ITaskItem[])items.ToArray(typeof(ITaskItem));

			// Log.HasLoggedErrors is true if the task logged any errors -- even if they were logged 
			// from a task's constructor or property setter. As long as this task is written to always log an error
			// when it fails, we can reliably return HasLoggedErrors.
			return !Log.HasLoggedErrors;
		}
	}
}
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