CustomAttributeNamedArgument Struct

  • Riferimento

Definizione

Spazio dei nomi:
System.Reflection
Assembly:
System.Reflection.dll
Assembly:
System.Runtime.dll
Assembly:
mscorlib.dll
Assembly:
netstandard.dll
Origine:
CustomAttributeNamedArgument.cs
Origine:
CustomAttributeNamedArgument.cs
Origine:
CustomAttributeNamedArgument.cs

Rappresenta un argomento denominato di un attributo personalizzato nel contesto di sola reflection.

public value class CustomAttributeNamedArgument
public value class CustomAttributeNamedArgument : IEquatable<System::Reflection::CustomAttributeNamedArgument>
public struct CustomAttributeNamedArgument
public readonly struct CustomAttributeNamedArgument
public readonly struct CustomAttributeNamedArgument : IEquatable<System.Reflection.CustomAttributeNamedArgument>
[System.Runtime.InteropServices.ComVisible(true)]
[System.Serializable]
public struct CustomAttributeNamedArgument
type CustomAttributeNamedArgument = struct
[<System.Runtime.InteropServices.ComVisible(true)>]
[<System.Serializable>]
type CustomAttributeNamedArgument = struct
Public Structure CustomAttributeNamedArgument
Public Structure CustomAttributeNamedArgument
Implements IEquatable(Of CustomAttributeNamedArgument)
Ereditarietà
Object
ValueType
CustomAttributeNamedArgument
Attributi
ComVisibleAttribute SerializableAttribute
Implementazioni
IEquatable<CustomAttributeNamedArgument>

Esempio

Nell'esempio seguente viene definito un attributo personalizzato con quattro costruttori e quattro proprietà. Due delle proprietà sono di sola lettura e vengono impostate usando i parametri posizionali dei costruttori. Le altre due proprietà sono di lettura/scrittura e possono essere impostate solo usando argomenti denominati. Una proprietà posizionale è una matrice di stringhe e una proprietà denominata è una matrice di numeri interi.

L'attributo viene applicato all'assembly, a un tipo dichiarato nell'assembly, a un metodo del tipo e a un parametro del metodo . Per questi casi vengono usati costruttori diversi. Quando viene eseguito, l'assembly viene caricato nel contesto di sola reflection e visualizza informazioni sugli attributi personalizzati applicati e al tipo e ai membri contenuti.

L'attributo applicato al tipo illustra le proprietà della matrice, con argomenti posizionali e denominati.

using namespace System;
using namespace System::Reflection;
using namespace System::Collections::Generic;
using namespace System::Collections::ObjectModel;

// An enumeration used by the ExampleAttribute class.
public enum class ExampleKind
{
   FirstKind, SecondKind, ThirdKind, FourthKind
};

// An example attribute. The attribute can be applied to all
// targets, from assemblies to parameters.
//
[AttributeUsage(AttributeTargets::All)]
public ref class ExampleAttribute: public Attribute
{
private:
   // Data for properties.
   ExampleKind kindValue;
   String^ noteValue;
   array<String^>^ arrayStrings;
   array<int>^ arrayNumbers;

   // Constructors. 
   void ExampleAttributeInitialize( ExampleKind initKind, array<String^>^ initStrings )
   {
      kindValue = initKind;
      arrayStrings = initStrings;
   }
public:
   ExampleAttribute()
   {
      ExampleAttributeInitialize( ExampleKind::FirstKind, nullptr );
   }
   ExampleAttribute( ExampleKind initKind )
   {
      ExampleAttributeInitialize( initKind, nullptr );
   }
   ExampleAttribute( ExampleKind initKind, array<String^>^ initStrings )
   {
      ExampleAttributeInitialize( initKind, initStrings );
   }

   // Properties. The Note and Numbers properties must be read/write, so they
   // can be used as named parameters.
   //
   property ExampleKind Kind 
   {
      ExampleKind get()
      {
         return kindValue;
      }
   }
   property array<String^>^ Strings
   {
      array<String^>^ get()
      {
         return arrayStrings;
      }
   }
   property String^ Note 
   {
      String^ get()
      {
         return noteValue;
      }

      void set( String^ value )
      {
         noteValue = value;
      }
   }
   property array<int>^ Numbers
   {
      array<int>^ get()
      {
         return arrayNumbers;
      }

      void set( array<int>^ value )
      {
         arrayNumbers = value;
      }
   }
};

// The example attribute is applied to the assembly.
[assembly:Example(ExampleKind::ThirdKind,Note="This is a note on the assembly.")];

// The example attribute is applied to the test class.
//
[Example(ExampleKind::SecondKind, 
         gcnew array<String^> { "String array argument, line 1", 
                        "String array argument, line 2", 
                        "String array argument, line 3" }, 
         Note="This is a note on the class.",
         Numbers = gcnew array<int> { 53, 57, 59 })] 
public ref class Test
{
public:
   // The example attribute is applied to a method, using the
   // parameterless constructor and supplying a named argument.
   // The attribute is also applied to the method parameter.
   //
   [Example(Note="This is a note on a method.")]
   void TestMethod( [Example] Object^ arg ){}

   // Main() gets objects representing the assembly, the test
   // type, the test method, and the method parameter. Custom
   // attribute data is displayed for each of these.
   //
   static void Main()
   {
      Assembly^ assembly = Assembly::ReflectionOnlyLoad( "Source" );
      Type^ t = assembly->GetType( "Test" );
      MethodInfo^ m = t->GetMethod( "TestMethod" );
      array<ParameterInfo^>^p = m->GetParameters();

      Console::WriteLine( "\r\nAttributes for assembly: '{0}'", assembly );
      ShowAttributeData( CustomAttributeData::GetCustomAttributes( assembly ) );
      Console::WriteLine( "\r\nAttributes for type: '{0}'", t );
      ShowAttributeData( CustomAttributeData::GetCustomAttributes( t ) );
      Console::WriteLine( "\r\nAttributes for member: '{0}'", m );
      ShowAttributeData( CustomAttributeData::GetCustomAttributes( m ) );
      Console::WriteLine( "\r\nAttributes for parameter: '{0}'", p );
      ShowAttributeData( CustomAttributeData::GetCustomAttributes( p[ 0 ] ) );
   }

private:
    static void ShowValueOrArray(CustomAttributeTypedArgument^ cata)
    {
        if (cata->Value->GetType() == ReadOnlyCollection<CustomAttributeTypedArgument>::typeid)
        {
            Console::WriteLine("         Array of '{0}':", cata->ArgumentType);

            for each (CustomAttributeTypedArgument^ cataElement in 
                (ReadOnlyCollection<CustomAttributeTypedArgument>^) cata->Value)
            {
                Console::WriteLine("             Type: '{0}'  Value: '{1}'",
                    cataElement->ArgumentType, cataElement->Value);
            }
        }
        else
        {
            Console::WriteLine( "         Type: '{0}'  Value: '{1}'",
               cata->ArgumentType, cata->Value );
        }
    }

   static void ShowAttributeData( IList< CustomAttributeData^ >^ attributes )
   {
      for each ( CustomAttributeData^ cad in attributes )
      {
         Console::WriteLine( "   {0}", cad );
         Console::WriteLine( "      Constructor: '{0}'", cad->Constructor );

         Console::WriteLine( "      Constructor arguments:" );
         for each ( CustomAttributeTypedArgument^ cata in cad->ConstructorArguments )
         {
            ShowValueOrArray(cata);
         }

         Console::WriteLine( "      Named arguments:" );
         for each ( CustomAttributeNamedArgument cana in cad->NamedArguments )
         {
            Console::WriteLine( "         MemberInfo: '{0}'", cana.MemberInfo );
            ShowValueOrArray(cana.TypedValue);
         }
      }
   }
};

int main()
{
   Test::Main();
}

/* This code example produces output similar to the following:

Attributes for assembly: 'source, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'
   [System.Runtime.CompilerServices.CompilationRelaxationsAttribute((Int32)8)]
      Constructor: 'Void .ctor(Int32)'
      Constructor arguments:
         Type: 'System.Int32'  Value: '8'
      Named arguments:
   [System.Runtime.CompilerServices.RuntimeCompatibilityAttribute(WrapNonExceptionThrows = True)]
      Constructor: 'Void .ctor()'
      Constructor arguments:
      Named arguments:
         MemberInfo: 'Boolean WrapNonExceptionThrows'
         Type: 'System.Boolean'  Value: 'True'
   [ExampleAttribute((ExampleKind)2, Note = "This is a note on the assembly.")]
      Constructor: 'Void .ctor(ExampleKind)'
      Constructor arguments:
         Type: 'ExampleKind'  Value: '2'
      Named arguments:
         MemberInfo: 'System.String Note'
         Type: 'System.String'  Value: 'This is a note on the assembly.'

Attributes for type: 'Test'
   [ExampleAttribute((ExampleKind)1, new String[3] { "String array argument, line 1", "String array argument, line 2", "String array argument, line 3" }, Note = "This is a note on the class.", Numbers = new Int32[3] { 53, 57, 59 })]
      Constructor: 'Void .ctor(ExampleKind, System.String[])'
      Constructor arguments:
         Type: 'ExampleKind'  Value: '1'
         Array of 'System.String[]':
             Type: 'System.String'  Value: 'String array argument, line 1'
             Type: 'System.String'  Value: 'String array argument, line 2'
             Type: 'System.String'  Value: 'String array argument, line 3'
      Named arguments:
         MemberInfo: 'System.String Note'
         Type: 'System.String'  Value: 'This is a note on the class.'
         MemberInfo: 'Int32[] Numbers'
         Array of 'System.Int32[]':
             Type: 'System.Int32'  Value: '53'
             Type: 'System.Int32'  Value: '57'
             Type: 'System.Int32'  Value: '59'

Attributes for member: 'Void TestMethod(System.Object)'
   [ExampleAttribute(Note = "This is a note on a method.")]
      Constructor: 'Void .ctor()'
      Constructor arguments:
      Named arguments:
         MemberInfo: 'System.String Note'
         Type: 'System.String'  Value: 'This is a note on a method.'

Attributes for parameter: 'System.Object arg'
   [ExampleAttribute()]
      Constructor: 'Void .ctor()'
      Constructor arguments:
      Named arguments:
*/

using System;
using System.Reflection;
using System.Collections.Generic;
using System.Collections.ObjectModel;

// The example attribute is applied to the assembly.
[assembly:Example(ExampleKind.ThirdKind, Note="This is a note on the assembly.")]

// An enumeration used by the ExampleAttribute class.
public enum ExampleKind
{
    FirstKind,
    SecondKind,
    ThirdKind,
    FourthKind
};

// An example attribute. The attribute can be applied to all
// targets, from assemblies to parameters.
//
[AttributeUsage(AttributeTargets.All)]
public class ExampleAttribute : Attribute
{
    // Data for properties.
    private ExampleKind kindValue;
    private string noteValue;
    private string[] arrayStrings;
    private int[] arrayNumbers;

    // Constructors. The parameterless constructor (.ctor) calls
    // the constructor that specifies ExampleKind and an array of
    // strings, and supplies the default values.
    //
    public ExampleAttribute(ExampleKind initKind, string[] initStrings)
    {
        kindValue = initKind;
        arrayStrings = initStrings;
    }
    public ExampleAttribute(ExampleKind initKind) : this(initKind, null) {}
    public ExampleAttribute() : this(ExampleKind.FirstKind, null) {}

    // Properties. The Note and Numbers properties must be read/write, so they
    // can be used as named parameters.
    //
    public ExampleKind Kind { get { return kindValue; }}
    public string[] Strings { get { return arrayStrings; }}
    public string Note
    {
        get { return noteValue; }
        set { noteValue = value; }
    }
    public int[] Numbers
    {
        get { return arrayNumbers; }
        set { arrayNumbers = value; }
    }
}

// The example attribute is applied to the test class.
//
[Example(ExampleKind.SecondKind,
         new string[] { "String array argument, line 1",
                        "String array argument, line 2",
                        "String array argument, line 3" },
         Note="This is a note on the class.",
         Numbers = new int[] { 53, 57, 59 })]
public class Test
{
    // The example attribute is applied to a method, using the
    // parameterless constructor and supplying a named argument.
    // The attribute is also applied to the method parameter.
    //
    [Example(Note="This is a note on a method.")]
    public void TestMethod([Example] object arg) { }

    // Main() gets objects representing the assembly, the test
    // type, the test method, and the method parameter. Custom
    // attribute data is displayed for each of these.
    //
    public static void Main()
    {
        Assembly asm = Assembly.ReflectionOnlyLoad("Source");
        Type t = asm.GetType("Test");
        MethodInfo m = t.GetMethod("TestMethod");
        ParameterInfo[] p = m.GetParameters();

        Console.WriteLine("\r\nAttributes for assembly: '{0}'", asm);
        ShowAttributeData(CustomAttributeData.GetCustomAttributes(asm));
        Console.WriteLine("\r\nAttributes for type: '{0}'", t);
        ShowAttributeData(CustomAttributeData.GetCustomAttributes(t));
        Console.WriteLine("\r\nAttributes for member: '{0}'", m);
        ShowAttributeData(CustomAttributeData.GetCustomAttributes(m));
        Console.WriteLine("\r\nAttributes for parameter: '{0}'", p);
        ShowAttributeData(CustomAttributeData.GetCustomAttributes(p[0]));
    }

    private static void ShowAttributeData(
        IList<CustomAttributeData> attributes)
    {
        foreach( CustomAttributeData cad in attributes )
        {
            Console.WriteLine("   {0}", cad);
            Console.WriteLine("      Constructor: '{0}'", cad.Constructor);

            Console.WriteLine("      Constructor arguments:");
            foreach( CustomAttributeTypedArgument cata
                in cad.ConstructorArguments )
            {
                ShowValueOrArray(cata);
            }

            Console.WriteLine("      Named arguments:");
            foreach( CustomAttributeNamedArgument cana
                in cad.NamedArguments )
            {
                Console.WriteLine("         MemberInfo: '{0}'",
                    cana.MemberInfo);
                ShowValueOrArray(cana.TypedValue);
            }
        }
    }

    private static void ShowValueOrArray(CustomAttributeTypedArgument cata)
    {
        if (cata.Value.GetType() == typeof(ReadOnlyCollection<CustomAttributeTypedArgument>))
        {
            Console.WriteLine("         Array of '{0}':", cata.ArgumentType);

            foreach (CustomAttributeTypedArgument cataElement in
                (ReadOnlyCollection<CustomAttributeTypedArgument>) cata.Value)
            {
                Console.WriteLine("             Type: '{0}'  Value: '{1}'",
                    cataElement.ArgumentType, cataElement.Value);
            }
        }
        else
        {
            Console.WriteLine("         Type: '{0}'  Value: '{1}'",
                cata.ArgumentType, cata.Value);
        }
    }
}

/* This code example produces output similar to the following:

Attributes for assembly: 'source, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'
   [System.Runtime.CompilerServices.CompilationRelaxationsAttribute((Int32)8)]
      Constructor: 'Void .ctor(Int32)'
      Constructor arguments:
         Type: 'System.Int32'  Value: '8'
      Named arguments:
   [System.Runtime.CompilerServices.RuntimeCompatibilityAttribute(WrapNonExceptionThrows = True)]
      Constructor: 'Void .ctor()'
      Constructor arguments:
      Named arguments:
         MemberInfo: 'Boolean WrapNonExceptionThrows'
         Type: 'System.Boolean'  Value: 'True'
   [ExampleAttribute((ExampleKind)2, Note = "This is a note on the assembly.")]
      Constructor: 'Void .ctor(ExampleKind)'
      Constructor arguments:
         Type: 'ExampleKind'  Value: '2'
      Named arguments:
         MemberInfo: 'System.String Note'
         Type: 'System.String'  Value: 'This is a note on the assembly.'

Attributes for type: 'Test'
   [ExampleAttribute((ExampleKind)1, new String[3] { "String array argument, line 1", "String array argument, line 2", "String array argument, line 3" }, Note = "This is a note on the class.", Numbers = new Int32[3] { 53, 57, 59 })]
      Constructor: 'Void .ctor(ExampleKind, System.String[])'
      Constructor arguments:
         Type: 'ExampleKind'  Value: '1'
         Array of 'System.String[]':
             Type: 'System.String'  Value: 'String array argument, line 1'
             Type: 'System.String'  Value: 'String array argument, line 2'
             Type: 'System.String'  Value: 'String array argument, line 3'
      Named arguments:
         MemberInfo: 'System.String Note'
         Type: 'System.String'  Value: 'This is a note on the class.'
         MemberInfo: 'Int32[] Numbers'
         Array of 'System.Int32[]':
             Type: 'System.Int32'  Value: '53'
             Type: 'System.Int32'  Value: '57'
             Type: 'System.Int32'  Value: '59'

Attributes for member: 'Void TestMethod(System.Object)'
   [ExampleAttribute(Note = "This is a note on a method.")]
      Constructor: 'Void .ctor()'
      Constructor arguments:
      Named arguments:
         MemberInfo: 'System.String Note'
         Type: 'System.String'  Value: 'This is a note on a method.'

Attributes for parameter: 'System.Object arg'
   [ExampleAttribute()]
      Constructor: 'Void .ctor()'
      Constructor arguments:
      Named arguments:
*/

Imports System.Reflection
Imports System.Collections.Generic
Imports System.Collections.ObjectModel

' The example attribute is applied to the assembly.
<Assembly:Example(ExampleKind.ThirdKind, Note:="This is a note on the assembly.")>

' An enumeration used by the ExampleAttribute class.
Public Enum ExampleKind
    FirstKind
    SecondKind
    ThirdKind
    FourthKind
End Enum

' An example attribute. The attribute can be applied to all
' targets, from assemblies to parameters.
'
<AttributeUsage(AttributeTargets.All)> _
Public Class ExampleAttribute
    Inherits Attribute

    ' Data for properties.
    Private kindValue As ExampleKind
    Private noteValue As String
    Private arrayStrings() As String
    Private arrayNumbers() As Integer

    ' Constructors. The parameterless constructor (.ctor) calls
    ' the constructor that specifies ExampleKind and an array of
    ' strings, and supplies the default values.
    '
    Public Sub New(ByVal initKind As ExampleKind, ByVal initStrings() As String)
        kindValue = initKind
        arrayStrings = initStrings
    End Sub
    Public Sub New(ByVal initKind As ExampleKind)
        Me.New(initKind, Nothing)
    End Sub
    Public Sub New()
        Me.New(ExampleKind.FirstKind, Nothing)
    End Sub

    ' Properties. The Note and Numbers properties must be read/write, so they 
    ' can be used as named parameters.
    '
    Public ReadOnly Property Kind As ExampleKind
        Get
            Return kindValue 
        End Get
    End Property
    Public ReadOnly Property Strings As String()
        Get
            Return arrayStrings 
        End Get
    End Property
    Public Property Note As String
        Get
            Return noteValue 
        End Get
        Set
            noteValue = value
        End Set
    End Property
    Public Property Numbers As Integer()
        Get
            Return arrayNumbers 
        End Get
        Set
            arrayNumbers = value
        End Set
    End Property
End Class

' The example attribute is applied to the test class.
'
<Example(ExampleKind.SecondKind, _
         New String() { "String array argument, line 1", _
                        "String array argument, line 2", _
                        "String array argument, line 3" }, _
         Note := "This is a note on the class.", _
         Numbers := New Integer() { 53, 57, 59 })> _
Public Class Test
    ' The example attribute is applied to a method, using the
    ' parameterless constructor and supplying a named argument.
    ' The attribute is also applied to the method parameter.
    '
    <Example(Note:="This is a note on a method.")> _
    Public Sub TestMethod(<Example()> ByVal arg As Object)
    End Sub

    ' Sub Main gets objects representing the assembly, the test
    ' type, the test method, and the method parameter. Custom
    ' attribute data is displayed for each of these.
    '
    Public Shared Sub Main()
        Dim asm As [Assembly] = Assembly.ReflectionOnlyLoad("source")
        Dim t As Type = asm.GetType("Test")
        Dim m As MethodInfo = t.GetMethod("TestMethod")
        Dim p() As ParameterInfo = m.GetParameters()

        Console.WriteLine(vbCrLf & "Attributes for assembly: '{0}'", asm)
        ShowAttributeData(CustomAttributeData.GetCustomAttributes(asm))
        Console.WriteLine(vbCrLf & "Attributes for type: '{0}'", t)
        ShowAttributeData(CustomAttributeData.GetCustomAttributes(t))
        Console.WriteLine(vbCrLf & "Attributes for member: '{0}'", m)
        ShowAttributeData(CustomAttributeData.GetCustomAttributes(m))
        Console.WriteLine(vbCrLf & "Attributes for parameter: '{0}'", p)
        ShowAttributeData(CustomAttributeData.GetCustomAttributes(p(0)))
    End Sub

    Private Shared Sub ShowAttributeData( _
        ByVal attributes As IList(Of CustomAttributeData))

        For Each cad As CustomAttributeData _
            In CType(attributes, IEnumerable(Of CustomAttributeData))

            Console.WriteLine("   {0}", cad)
            Console.WriteLine("      Constructor: '{0}'", cad.Constructor)

            Console.WriteLine("      Constructor arguments:")
            For Each cata As CustomAttributeTypedArgument _
                In CType(cad.ConstructorArguments, IEnumerable(Of CustomAttributeTypedArgument))

                ShowValueOrArray(cata)
            Next

            Console.WriteLine("      Named arguments:")
            For Each cana As CustomAttributeNamedArgument _
                In CType(cad.NamedArguments, IEnumerable(Of CustomAttributeNamedArgument))

                Console.WriteLine("         MemberInfo: '{0}'", _
                    cana.MemberInfo)
                ShowValueOrArray(cana.TypedValue)
            Next
        Next
    End Sub

    Private Shared Sub ShowValueOrArray(ByVal cata As CustomAttributeTypedArgument)
        If cata.Value.GetType() Is GetType(ReadOnlyCollection(Of CustomAttributeTypedArgument)) Then
            Console.WriteLine("         Array of '{0}':", cata.ArgumentType)

            For Each cataElement As CustomAttributeTypedArgument In cata.Value
                Console.WriteLine("             Type: '{0}'  Value: '{1}'", _
                    cataElement.ArgumentType, cataElement.Value)
            Next
        Else
            Console.WriteLine("         Type: '{0}'  Value: '{1}'", _
                cata.ArgumentType, cata.Value)
        End If       
    End Sub
End Class

' This code example produces output similar to the following:
'
'Attributes for assembly: 'source, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null'
'   [System.Runtime.CompilerServices.CompilationRelaxationsAttribute((Int32)8)]
'      Constructor: 'Void .ctor(Int32)'
'      Constructor arguments:
'         Type: 'System.Int32'  Value: '8'
'      Named arguments:
'   [System.Runtime.CompilerServices.RuntimeCompatibilityAttribute(WrapNonExceptionThrows = True)]
'      Constructor: 'Void .ctor()'
'      Constructor arguments:
'      Named arguments:
'         MemberInfo: 'Boolean WrapNonExceptionThrows'
'         Type: 'System.Boolean'  Value: 'True'
'   [ExampleAttribute((ExampleKind)2, Note = "This is a note on the assembly.")]
'      Constructor: 'Void .ctor(ExampleKind)'
'      Constructor arguments:
'         Type: 'ExampleKind'  Value: '2'
'      Named arguments:
'         MemberInfo: 'System.String Note'
'         Type: 'System.String'  Value: 'This is a note on the assembly.'
'
'Attributes for type: 'Test'
'   [ExampleAttribute((ExampleKind)1, new String[3] { "String array argument, line 1", "String array argument, line 2", "String array argument, line 3" }, Note = "This is a note on the class.", Numbers = new Int32[3] { 53, 57, 59 })]
'      Constructor: 'Void .ctor(ExampleKind, System.String[])'
'      Constructor arguments:
'         Type: 'ExampleKind'  Value: '1'
'         Array of 'System.String[]':
'             Type: 'System.String'  Value: 'String array argument, line 1'
'             Type: 'System.String'  Value: 'String array argument, line 2'
'             Type: 'System.String'  Value: 'String array argument, line 3'
'      Named arguments:
'         MemberInfo: 'System.String Note'
'         Type: 'System.String'  Value: 'This is a note on the class.'
'         MemberInfo: 'Int32[] Numbers'
'         Array of 'System.Int32[]':
'             Type: 'System.Int32'  Value: '53'
'             Type: 'System.Int32'  Value: '57'
'             Type: 'System.Int32'  Value: '59'
'
'Attributes for member: 'Void TestMethod(System.Object)'
'   [ExampleAttribute(Note = "This is a note on a method.")]
'      Constructor: 'Void .ctor()'
'      Constructor arguments:
'      Named arguments:
'         MemberInfo: 'System.String Note'
'         Type: 'System.String'  Value: 'This is a note on a method.'
'
'Attributes for parameter: 'System.Object arg'
'   [ExampleAttribute()]
'      Constructor: 'Void .ctor()'
'      Constructor arguments:
'      Named arguments:

Commenti

Il codice esaminato nel contesto di sola reflection non può essere eseguito, quindi non è sempre possibile esaminare gli attributi personalizzati creando istanze di tali attributi e quindi esaminandone le proprietà, usando metodi come Attribute.GetCustomAttributes, MemberInfo.GetCustomAttributese così via. Se il codice per il tipo di attributo stesso viene caricato nel contesto di sola reflection, non può essere eseguito.

La struttura CustomAttributeNamedArgument viene utilizzata dalla classe CustomAttributeData per fornire l'accesso a un argomento denominato specificato per un'istanza dell'attributo personalizzato, senza eseguire il codice della proprietà corrispondente del tipo di attributo personalizzato. La proprietà TypedValue restituisce una struttura CustomAttributeTypedArgument che contiene il tipo e il valore dell'argomento denominato.

Importante

Indipendentemente dal fatto che un argomento sia denominato o posizionale, è necessario accedere al tipo e al valore usando la struttura CustomAttributeTypedArgument.

Per creare istanze della classe CustomAttributeData, usare il metodo factory staticGetCustomAttributes.

Costruttori

CustomAttributeNamedArgument(MemberInfo, CustomAttributeTypedArgument)

Inizializza una nuova istanza della classe CustomAttributeNamedArgument, che rappresenta il campo o la proprietà specificati dell'attributo personalizzato e specifica un oggetto CustomAttributeTypedArgument che descrive il tipo e il valore del campo o della proprietà.
CustomAttributeNamedArgument(MemberInfo, Object)

Inizializza una nuova istanza della classe CustomAttributeNamedArgument, che rappresenta il campo o la proprietà specificati dell'attributo personalizzato e specifica il valore del campo o della proprietà.

Proprietà

IsField

Ottiene un valore che indica se l'argomento denominato è un campo.
MemberInfo

Ottiene il membro dell'attributo che verrà utilizzato per impostare l'argomento denominato.
MemberName

Ottiene il nome del membro dell'attributo che verrà utilizzato per impostare l'argomento denominato.
TypedValue

Ottiene una struttura CustomAttributeTypedArgument che può essere utilizzata per ottenere il tipo e il valore dell'argomento denominato corrente.

Metodi

Equals(CustomAttributeNamedArgument)

Indica se l'istanza corrente è uguale a un'altra istanza dello stesso tipo.
Equals(Object)

Restituisce un valore che indica se questa istanza è uguale a un oggetto specificato.
GetHashCode()

Restituisce il codice hash per questa istanza.
ToString()

Restituisce una stringa costituita dal nome dell'argomento, dal segno di uguale e da una rappresentazione di stringa del valore dell'argomento.

Operatori

Equality(CustomAttributeNamedArgument, CustomAttributeNamedArgument)

Verifica se due strutture CustomAttributeNamedArgument sono equivalenti.
Inequality(CustomAttributeNamedArgument, CustomAttributeNamedArgument)

Verifica se due strutture CustomAttributeNamedArgument sono diverse.

Si applica a

Vedi anche