DebuggerTypeProxyAttribute Class

Definition

Namespace:

System.Diagnostics

Assembly:

System.Runtime.dll

Source:

DebuggerTypeProxyAttribute.cs

Specifies the display proxy for a type.

public ref class DebuggerTypeProxyAttribute sealed : Attribute

[System.AttributeUsage(System.AttributeTargets.Assembly | System.AttributeTargets.Class | System.AttributeTargets.Struct, AllowMultiple=true)]
public sealed class DebuggerTypeProxyAttribute : Attribute

[<System.AttributeUsage(System.AttributeTargets.Assembly | System.AttributeTargets.Class | System.AttributeTargets.Struct, AllowMultiple=true)>]
type DebuggerTypeProxyAttribute = class
    inherit Attribute

Public NotInheritable Class DebuggerTypeProxyAttribute
Inherits Attribute

Inheritance

Object

Attribute

DebuggerTypeProxyAttribute

Attributes

AttributeUsageAttribute

Examples

The following code example shows the use of the DebuggerTypeProxyAttribute to specify a private nested type to be used as a debugger display proxy. This code example is part of a larger example provided for the DebuggerDisplayAttribute class.

[DebuggerTypeProxy(HashtableDebugView::typeid)]
ref class MyHashtable : Hashtable
{
private:
    static const String^ TestString = "This should not appear in the debug window.";

internal:
    ref class HashtableDebugView
    {
    private:
        Hashtable^ hashtable;
    public:
        static const String^ TestString = "This should appear in the debug window.";
        HashtableDebugView(Hashtable^ hashtable)
        {
            this->hashtable = hashtable;
        }

        [DebuggerBrowsable(DebuggerBrowsableState::RootHidden)]
        property array<KeyValuePairs^>^ Keys
        {
            array<KeyValuePairs^>^ get()
            {
                array<KeyValuePairs^>^ keys = gcnew array<KeyValuePairs^>(hashtable->Count);

                IEnumerator^ ie = hashtable->Keys->GetEnumerator();
                int i = 0;
                Object^ key;
                while (ie->MoveNext())
                {
                    key = ie->Current;
                    keys[i] = gcnew KeyValuePairs(hashtable, key, hashtable[key]);
                    i++;
                }
                return keys;
            }
        }
    };
};

[DebuggerTypeProxy(typeof(HashtableDebugView))]
class MyHashtable : Hashtable
{
    private const string TestString = "This should not appear in the debug window.";

    internal class HashtableDebugView
    {
        private Hashtable hashtable;
        public const string TestString = "This should appear in the debug window.";
        public HashtableDebugView(Hashtable hashtable)
        {
            this.hashtable = hashtable;
        }

        [DebuggerBrowsable(DebuggerBrowsableState.RootHidden)]
        public KeyValuePairs[] Keys
        {
            get
            {
                KeyValuePairs[] keys = new KeyValuePairs[hashtable.Count];

                int i = 0;
                foreach(object key in hashtable.Keys)
                {
                    keys[i] = new KeyValuePairs(hashtable, key, hashtable[key]);
                    i++;
                }
                return keys;
            }
        }
    }
}

<DebuggerDisplay("Count = {Count}"), DebuggerTypeProxy(GetType(MyHashtable.HashtableDebugView))> _
Class MyHashtable
    Inherits Hashtable
    Private Const TestString As String = "This should not appear in the debug window."

    Friend Class HashtableDebugView
        Private hashtable As Hashtable
        Public Shared TestString As String = "This should appear in the debug window."

        Public Sub New(ByVal hashtable As Hashtable)
            Me.hashtable = hashtable
        End Sub

        <DebuggerBrowsable(DebuggerBrowsableState.RootHidden)> _
        ReadOnly Property Keys as KeyValuePairs()
            Get
                Dim nkeys(hashtable.Count) as KeyValuePairs

                Dim i as Integer = 0
                For Each key As Object In hashtable.Keys
                    nkeys(i) = New KeyValuePairs(hashtable, key, hashtable(key))
                    i = i + 1
                Next
                Return nkeys
            End Get
        End Property

    End Class
End Class

Remarks

Note Use this attribute when you need to significantly and fundamentally change the debugging view of a type, but not change the type itself.

The DebuggerTypeProxyAttribute attribute is used to specify a display proxy for a type, allowing a developer to tailor the view for the type. This attribute can be used at the assembly level as well, in which case the Target property specifies the type for which the proxy will be used. In general, this attribute specifies a private nested type that occurs within the type to which the attribute is applied. An expression evaluator that supports type viewers checks for this attribute when a type is displayed. If the attribute is found, the expression evaluator substitutes the display proxy type for the type the attribute is applied to.

When the DebuggerBrowsableAttribute is present, the debugger variable window displays only the public members of the proxy type. Private members are not displayed. The behavior of the data window is not changed by attribute-enhanced views.

To avoid unnecessary performance penalties, expression evaluators should not examine the attributes on the display proxy of the type unless the type is expanded, either through the user clicking the plus sign (+) next to the type in a data window, or through the application of the DebuggerBrowsableAttribute attribute. Therefore, it is recommended that no attributes be applied to the display type. Attributes can and should be applied within the body of the display type.

Constructors

DebuggerTypeProxyAttribute(String)	Initializes a new instance of the DebuggerTypeProxyAttribute class using the type name of the proxy.
DebuggerTypeProxyAttribute(Type)	Initializes a new instance of the DebuggerTypeProxyAttribute class using the type of the proxy.

Properties

ProxyTypeName	Gets the type name of the proxy type.
Target	Gets or sets the target type for the attribute.
TargetTypeName	Gets or sets the name of the target type.
TypeId	When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute)

Methods

Equals(Object)	Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute)
GetHashCode()	Returns the hash code for this instance. (Inherited from Attribute)
GetType()	Gets the Type of the current instance. (Inherited from Object)
IsDefaultAttribute()	When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute)
Match(Object)	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Returns a string that represents the current object. (Inherited from Object)

See also

• Using DebuggerTypeProxy Attribute