Článek
11/17/2011

FieldAttributes Enumeration

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Specifies the attributes of a field.

This enumeration has a FlagsAttribute attribute that allows a bitwise combination of its member values.

Namespace: System.Reflection
Assembly: mscorlib (in mscorlib.dll)

Syntax

'Declaration
<ComVisibleAttribute(True)> _
<FlagsAttribute> _
Public Enumeration FieldAttributes

[ComVisibleAttribute(true)]
[FlagsAttribute]
public enum FieldAttributes

Members

	Member name	Description
	FieldAccessMask	Specifies the access level of a given field.
	PrivateScope	The field cannot be referenced.
	Private	The field is accessible only by the parent type.
	FamANDAssem	The field is accessible only by subtypes in this assembly.
	Assembly	The field is accessible throughout the assembly.
	Family	The field is accessible only by type and subtypes.
	FamORAssem	The field is accessible by subtypes anywhere, as well as throughout this assembly.
	Public	The field is accessible by any member for whom this scope is visible.
	Static	The field represents the defined type, or else it is per-instance.
	InitOnly	The field is initialized only, and cannot be written after initialization.
	Literal	The field's value is a compile-time (static or early bound) constant. Any attempt to set it throws FieldAccessException.
	NotSerialized	The field does not have to be serialized when the type is remoted.
	SpecialName	Specifies a special field, with the name describing how the field is special.
	PinvokeImpl	Reserved.
	ReservedMask	Reserved.
	RTSpecialName	The common language runtime (internal metadata APIs) should check the name encoding.
	HasFieldMarshal	The field has marshaling information.
	HasDefault	The field has a default value.
	HasFieldRVA	The field has a relative virtual address (RVA). The RVA is the location of the method body in the current image, as an address relative to the start of the image file in which it is located.

Remarks

FieldAttributes uses the value from FieldAccessMask to mask off only the parts of the attribute value that pertain to the accessibility. For example, the following code determines if Attributes has the public bit set:

If (Attributes And FieldAttributes.FieldAccessMask) = _
    FieldAttributes.Public Then

if ((Attributes & FieldAttributes.FieldAccessMask) == 
    FieldAttributes.Public)

To get the FieldAttributes, first get the class Type. From the Type, get the FieldInfo. From the FieldInfo, get the Attributes.

The enumerated value is a number representing the bitwise OR of the attributes implemented on the field.

Examples

This example shows how to test for the enumeration members that describe access level.

Note:
To run this example, see Building Examples That Use a Demo Method and a TextBlock Control.

Imports System.Reflection

Public Class Example
   ' 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"


   ' Make the output TextBlock visible to all Shared members.
   Private Shared outputBlock As System.Windows.Controls.TextBlock

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      Example.outputBlock = outputBlock

      ' Create an instance of the Example class.
      Dim ex As New Example()

      outputBlock.Text &= vbCrLf & "Reflection.FieldAttributes" & vbCrLf

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

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

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

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

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

      Dim value As Object = "<not accessible>"
      If f.IsPublic Then
         value = f.GetValue(obj)
      End If

      ' Display the field name, value, and attributes.
      '
      outputBlock.Text &= String.Format("{0} = ""{1}""; attributes: {2}", _
          f.Name, value.ToString(), f.Attributes) & vbCrLf
   End Sub

End Class

' This code example produces the following output:
'
'm_field = "<not accessible>"; attributes: Private
'Field = "String B"; attributes: Public
'FieldC = "String C"; attributes: Public, Static, Literal, HasDefault

using System;
using System.Reflection;

public class Example
{
   // 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";


   // Make the output TextBlock visible to all Shared members.
   static System.Windows.Controls.TextBlock outputBlock;

   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      Example.outputBlock = outputBlock;

      outputBlock.Text += "\nReflection.FieldAttributes\n";
      Example ex = new Example();

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

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

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

   static void DisplayField(Object obj, FieldInfo f)
   {
      object value = "<not accessible>";
      if (f.IsPublic)
      {
         value = f.GetValue(obj);
      }

      // Display the field name, value, and attributes.
      //
      outputBlock.Text += String.Format("{0} = \"{1}\"; attributes: {2}\n",
          f.Name, value.ToString(), f.Attributes);
   }
}

/* This code example produces the following output:

Reflection.FieldAttributes
m_field = "<not accessible>"; attributes: Private
Field = "String B"; attributes: Public
FieldC = "String C"; attributes: Public, Static, Literal, HasDefault
 */

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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