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HelpKeywordAttribute Class

Specifies the context keyword for a class or member. This class cannot be inherited.

System.Object
  System.Attribute
    System.ComponentModel.Design.HelpKeywordAttribute

Namespace:  System.ComponentModel.Design
Assembly:  System (in System.dll)

[SerializableAttribute]
[AttributeUsageAttribute(AttributeTargets.All, AllowMultiple = false, Inherited = false)]
public sealed class HelpKeywordAttribute : Attribute

The HelpKeywordAttribute type exposes the following members.

  NameDescription
Public methodHelpKeywordAttribute()Initializes a new instance of the HelpKeywordAttribute class.
Public methodHelpKeywordAttribute(String)Initializes a new instance of the HelpKeywordAttribute class.
Public methodHelpKeywordAttribute(Type)Initializes a new instance of the HelpKeywordAttribute class from the given type.
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  NameDescription
Public propertyHelpKeywordGets the Help keyword supplied by this attribute.
Public propertyTypeIdWhen implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute.)
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  NameDescription
Public methodEqualsDetermines whether two HelpKeywordAttribute instances are equal. (Overrides Attribute.Equals(Object).)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetHashCodeReturns the hash code for this instance. (Overrides Attribute.GetHashCode().)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodIsDefaultAttributeDetermines whether the Help keyword is null. (Overrides Attribute.IsDefaultAttribute().)
Public methodMatchWhen overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Public fieldStatic memberDefaultRepresents the default value for HelpKeywordAttribute. This field is read-only.
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  NameDescription
Explicit interface implemetationPrivate method_Attribute.GetIDsOfNamesMaps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoRetrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.GetTypeInfoCountRetrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
Explicit interface implemetationPrivate method_Attribute.InvokeProvides access to properties and methods exposed by an object. (Inherited from Attribute.)
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By default, the Help keyword for a class is given by the Type.FullName property value. For members, the Help keyword is given by the full name of the type that declared the property, plus the property name itself.

For example, consider the Control.Text property on the System.Windows.Forms.Button control. The class keyword is "System.Windows.Forms.Button", but the Control.Text property keyword is "System.Windows.Forms.Control.Text", because the Control.Text property is declared on the System.Windows.Forms.Control class, rather than the System.Windows.Forms.Button class itself; the System.Windows.Forms.Button class inherits the property.

By contrast, the Button.DialogResult property is declared on the System.Windows.Forms.Button class, so its keyword is "System.Windows.Forms.Button.DialogResult".

When the Help system gets the keywords, it will first look at HelpKeywordAttribute. At the class level, it will return the string specified by the HelpKeywordAttribute. This will not be used for members of the type in question, which will still reflect the declaring type's actual full name, plus the member name. This attribute supports strongly typed classes that have associated common documentation but distinct Help IDs.

The following code example shows how to override this Help system behavior by placing the attribute on the member itself. These are the keywords for the following class, called DemoComponent:

  • Class keyword: "System.ComponentModel.Component" (DemoNamespace.DemoComponent)

  • Property1 keyword: "DemoNamespace.DemoComponent.Property1" (default)

  • Property2 keyword: "SomeNamespace.SomeOtherClass.Property2" (DemoNamespace.DemoComponent.Property2)

[HelpKeywordAttribute(typeof(Component))]
public class DemoComponent : Component
{
    public string Property1
    {
        get
        {
            return "";
        }
    }

    [HelpKeywordAttribute("SomeNamespace.SomeOtherClass.Property2")]
    public string Property2
    {
        get
        {
            return "";
        }
    }
}

The following code example demonstrates using the HelpKeywordAttribute class to specify a context keyword. For a complete explanation of this code example, see How to: Apply Attributes in Windows Forms Controls.


// This control demonstrates a simple logging capability. 
[ComplexBindingProperties("DataSource", "DataMember")]
[DefaultBindingProperty("TitleText")]
[DefaultEvent("ThresholdExceeded")]
[DefaultProperty("Threshold")]
[HelpKeywordAttribute(typeof(UserControl))]
[ToolboxItem("System.Windows.Forms.Design.AutoSizeToolboxItem,System.Design")]
public class AttributesDemoControl : UserControl
{


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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