OutputAttribute Class
Defines the metadata attribute that task authors use to identify task properties that output data from 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.
Inheritance Hierarchy
System.Object
System.Attribute
Microsoft.Build.Framework.OutputAttribute
Namespace: Microsoft.Build.Framework
Assembly: Microsoft.Build.Framework (in Microsoft.Build.Framework.dll)
Syntax
'Declaration
<AttributeUsageAttribute(AttributeTargets.Property, AllowMultiple := False, _
Inherited := False)> _
Public NotInheritable Class OutputAttribute _
Inherits Attribute
[AttributeUsageAttribute(AttributeTargets.Property, AllowMultiple = false,
Inherited = false)]
public sealed class OutputAttribute : Attribute
[AttributeUsageAttribute(AttributeTargets::Property, AllowMultiple = false,
Inherited = false)]
public ref class OutputAttribute sealed : public Attribute
[<Sealed>]
[<AttributeUsageAttribute(AttributeTargets.Property, AllowMultiple = false,
Inherited = false)>]
type OutputAttribute =
class
inherit Attribute
end
public final class OutputAttribute extends Attribute
The OutputAttribute type exposes the following members.
Constructors
| Name | Description | |
|---|---|---|
.gif "Public method") |
OutputAttribute | Initializes a new instance of the OutputAttribute class.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. |
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Properties
| Name | Description | |
|---|---|---|
.gif "Public property") |
TypeId | (Inherited from Attribute.) |
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Methods
| Name | Description | |
|---|---|---|
|
Equals | (Inherited from Attribute.) |
|
GetHashCode | (Inherited from Attribute.) |
|
GetType | (Inherited from Object.) |
|
IsDefaultAttribute | (Inherited from Attribute.) |
|
Match | (Inherited from Attribute.) |
|
ToString | (Inherited from Object.) |
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Explicit Interface Implementations
| Name | Description | |
|---|---|---|
.gif "Explicit interface implemetation") .gif "Private method") |
System#Runtime#InteropServices#_Attribute#GetIDsOfNames | (Inherited from Attribute.) |
|
System#Runtime#InteropServices#_Attribute#GetTypeInfo | (Inherited from Attribute.) |
|
System#Runtime#InteropServices#_Attribute#GetTypeInfoCount | (Inherited from Attribute.) |
|
System#Runtime#InteropServices#_Attribute#Invoke | (Inherited from Attribute.) |
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Remarks
The MSBuild engine will only allow task properties marked with this attribute to output data from a task. Project authors can only use properties marked with this attribute in the Output element of a project file. All other task properties are treated as inputs to a task.
For more information about using attributes, see Extending Metadata Using Attributes.
Examples
The following example shows the code for a task that creates one or more directories.
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;
}
}
}
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.