FieldAttributes Enumerazione

Definizione

public enum class FieldAttributes

[System.Flags]
public enum FieldAttributes

[System.Flags]
[System.Serializable]
public enum FieldAttributes

[System.Flags]
[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public enum FieldAttributes

[<System.Flags>]
type FieldAttributes = 

[<System.Flags>]
[<System.Serializable>]
type FieldAttributes = 

[<System.Flags>]
[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type FieldAttributes = 

Public Enum FieldAttributes

Ereditarietà

Object

ValueType

Enum

FieldAttributes

Attributi

FlagsAttribute SerializableAttribute ComVisibleAttribute

Campi

Esempio

In questo esempio vengono compilati tre campi e vengono visualizzati i FieldAttributes valori. Un FieldAttributes valore può contenere più di un attributo, ad esempio, sia Public che Literal, come illustrato nel terzo campo.

using namespace System;
using namespace System::Reflection;
using namespace System::Security::Permissions;

public ref class Demo
{
private:
    // Make three fields:
    // The first field is private.
    String^ m_field;

    // The second field is public.
public:
    String^ Field;

    // The third field is public and literal. 
    literal String^ FieldC = "String C";

    Demo() { m_field = "String A"; Field = "String B"; }
};

static void DisplayField(Object^ obj, FieldInfo^ f)
{ 
    // Display the field name, value, and attributes.
    //
    Console::WriteLine("{0} = \"{1}\"; attributes: {2}", 
        f->Name, f->GetValue(obj), f->Attributes);
};

void main()
{
    Console::WriteLine ("\nReflection.FieldAttributes");
    Demo^ d = gcnew Demo();

    // Get a Type object for Demo, and a FieldInfo for each of
    // the three fields. Use the FieldInfo to display field
    // name, value for the Demo object in d, and attributes.
    //
    Type^ myType = Demo::typeid;

    FieldInfo^ fiPrivate = myType->GetField("m_field",
        BindingFlags::NonPublic | BindingFlags::Instance);
    DisplayField(d, fiPrivate);

    FieldInfo^ fiPublic = myType->GetField("Field",
        BindingFlags::Public | BindingFlags::Instance);
    DisplayField(d, fiPublic);

    FieldInfo^ fiConstant = myType->GetField("FieldC",
        BindingFlags::Public | BindingFlags::Static);
    DisplayField(d, fiConstant);
}

/* This code example produces the following output:

Reflection.FieldAttributes
m_field = "String A"; attributes: Private
Field = "String B"; attributes: Public
FieldC = "String C"; attributes: Public, Static, Literal, HasDefault
 */

using System;
using System.Reflection;

public class Demo
{
    // Make three fields:
    // The first field is private.
    private string m_field = "String A";

    // The second field is public.
    public string Field = "String B";

    // The third field is public const (hence also literal and static),
    // with a default value.
    public const string FieldC = "String C";
}

public class Myfieldattributes
{
    public static void Main()
    {
        Console.WriteLine ("\nReflection.FieldAttributes");
        Demo d = new Demo();

        // Get a Type object for Demo, and a FieldInfo for each of
        // the three fields. Use the FieldInfo to display field
        // name, value for the Demo object in d, and attributes.
        //
        Type myType = typeof(Demo);
        FieldInfo fiPrivate = myType.GetField("m_field",
            BindingFlags.NonPublic | BindingFlags.Instance);
        DisplayField(d, fiPrivate);

        FieldInfo fiPublic = myType.GetField("Field",
            BindingFlags.Public | BindingFlags.Instance);
        DisplayField(d, fiPublic);

        FieldInfo fiConstant = myType.GetField("FieldC",
            BindingFlags.Public | BindingFlags.Static);
        DisplayField(d, fiConstant);
    }

    static void DisplayField(Object obj, FieldInfo f)
    {
        // Display the field name, value, and attributes.
        //
        Console.WriteLine("{0} = \"{1}\"; attributes: {2}",
            f.Name, f.GetValue(obj), f.Attributes);
    }
}

/* This code example produces the following output:

Reflection.FieldAttributes
m_field = "String A"; attributes: Private
Field = "String B"; attributes: Public
FieldC = "String C"; attributes: Public, Static, Literal, HasDefault
 */

Imports System.Reflection

Public Class Demo
    ' Declare three fields.
    ' The first field is private.
    Private m_field As String = "String A"

    'The second field is public.
    Public Field As String = "String B"

    ' The third field is public and const, hence also static
    ' and literal with a default value.
    Public Const FieldC As String = "String C"

End Class

Module Module1
    Sub Main()
        ' Create an instance of the Demo class.
        Dim d As New Demo()

        Console.WriteLine(vbCrLf & "Reflection.FieldAttributes")

        ' Get a Type object for Demo, and a FieldInfo for each of
        ' the three fields. Use the FieldInfo to display field
        ' name, value for the Demo object in d, and attributes.
        '
        Dim myType As Type = GetType(Demo)

        Dim fiPrivate As FieldInfo = myType.GetField("m_field", _
            BindingFlags.NonPublic Or BindingFlags.Instance)
        DisplayField(d, fiPrivate)

        Dim fiPublic As FieldInfo = myType.GetField("Field", _
            BindingFlags.Public Or BindingFlags.Instance)
        DisplayField(d, fiPublic)

        Dim fiConstant As FieldInfo = myType.GetField("FieldC", _
            BindingFlags.Public Or BindingFlags.Static)
        DisplayField(d, fiConstant)
    End Sub

    Sub DisplayField(ByVal obj As Object, ByVal f As FieldInfo)

        ' Display the field name, value, and attributes.
        '
        Console.WriteLine("{0} = ""{1}""; attributes: {2}", _
            f.Name, f.GetValue(obj), f.Attributes)
    End Sub

End Module

' This code example produces the following output:
'
'm_field = "String A"; attributes: Private
'Field = "String B"; attributes: Public
'FieldC = "String C"; attributes: Public, Static, Literal, HasDefault

Commenti

FieldAttributes usa il valore da FieldAccessMask per mascherare solo le parti del valore dell'attributo che riguardano l'accessibilità. Ad esempio, il codice seguente determina se Attributes il bit pubblico è impostato.

FieldInfo^ fi = obj->GetType()->GetField("field1");

if ((fi->Attributes & FieldAttributes::FieldAccessMask) ==
    FieldAttributes::Public)
{
    Console::WriteLine("{0:s} is public. Value: {1:d}", fi->Name, fi->GetValue(obj));
}

FieldInfo fi = obj.GetType().GetField("field1");

if ((fi.Attributes & FieldAttributes.FieldAccessMask) ==
    FieldAttributes.Public)
{
    Console.WriteLine("{0:s} is public. Value: {1:d}", fi.Name, fi.GetValue(obj));
}

Dim fi As FieldInfo = obj.GetType().GetField("field1")

If (fi.Attributes And FieldAttributes.FieldAccessMask) = _
    FieldAttributes.Public Then
    Console.WriteLine("{0:s} is public. Value: {1:d}", fi.Name, fi.GetValue(obj))
End If

Per ottenere FieldAttributes, ottenere prima di tutto la classe Type. Da ottenere l'oggetto TypeFieldInfo. Da ottenere l'oggetto FieldInfoAttributes.

Il valore enumerato è un numero che rappresenta l'OR bit per bit degli attributi implementati nel campo.

Si applica a