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AttributeProviderAttribute Class

Enables attribute redirection. This class cannot be inherited.

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

[AttributeUsageAttribute(AttributeTargets.Property)] 
public class AttributeProviderAttribute : Attribute
/** @attribute AttributeUsageAttribute(AttributeTargets.Property) */ 
public class AttributeProviderAttribute extends Attribute
AttributeUsageAttribute(AttributeTargets.Property) 
public class AttributeProviderAttribute extends Attribute
Not applicable.

There are a few cases in the .NET Framework object model where a property is purposely typed to be vague. For example, the DataGridView.DataSource property is typed as object. The reason for this is that this property can accept several types of input. Unfortunately, this provides no common place to add metadata to describe the characteristics of the property. Each DataSource property throughout the .NET Framework needs to have identical metadata for type converters, UI type editors, and other services that require metadata. The AttributeProviderAttribute remedies this situation.

Once this attribute is placed on a property, the rules for obtaining attributes for the property descriptor's MemberDescriptor.Attributes collection differ. Typically, the property descriptor gathers local attributes, and then merges these with attributes from the property type. In this case, the attributes are taken from the type returned from the AttributeProviderAttribute, not from the actual property type. This attribute is used on DataGridView.DataSource to point the DataGridView.DataSource object's specific type to IListSource, and the appropriate metadata is placed on IListSource to enable data binding. In so doing, external parties can easily add metadata to all data sources.

Attributes obtained from a type declared in the AttributeProviderAttribute have a priority in between the attributes of the property’s type and the attributes on the property. The following list, in priority order, shows the full set of available merged attributes:

  • Property Attributes

  • Attribute Provider Attributes

  • Property Type Attributes

The following code example demonstrates using AttributeProviderAttribute to mark a DataSource property with a specific type of IListSource. For a full code listing, see How to: Apply Attributes in Windows Forms Controls.

[Category("Data")]
[Description("Indicates the source of data for the control.")]
[RefreshProperties(RefreshProperties.Repaint)]
[AttributeProvider(typeof(IListSource))]
public object DataSource
{
    get
    {
        return this.dataGridView1.DataSource;
    }

    set
    {
        this.dataGridView1.DataSource = value;
    }
}

System.Object
   System.Attribute
    System.ComponentModel.AttributeProviderAttribute

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

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

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