FieldBuilder Class

Definition

Defines and represents a field. This class cannot be inherited.

public ref class FieldBuilder sealed : System::Reflection::FieldInfo
public ref class FieldBuilder sealed : System::Reflection::FieldInfo, System::Runtime::InteropServices::_FieldBuilder
public ref class FieldBuilder abstract : System::Reflection::FieldInfo
public sealed class FieldBuilder : System.Reflection.FieldInfo
[System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.None)]
public sealed class FieldBuilder : System.Reflection.FieldInfo, System.Runtime.InteropServices._FieldBuilder
[System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.None)]
[System.Runtime.InteropServices.ComVisible(true)]
public sealed class FieldBuilder : System.Reflection.FieldInfo, System.Runtime.InteropServices._FieldBuilder
public abstract class FieldBuilder : System.Reflection.FieldInfo
type FieldBuilder = class
    inherit FieldInfo
[<System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.None)>]
type FieldBuilder = class
    inherit FieldInfo
    interface _FieldBuilder
[<System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.None)>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type FieldBuilder = class
    inherit FieldInfo
    interface _FieldBuilder
Public NotInheritable Class FieldBuilder
Inherits FieldInfo
Public NotInheritable Class FieldBuilder
Inherits FieldInfo
Implements _FieldBuilder
Public MustInherit Class FieldBuilder
Inherits FieldInfo
Inheritance
FieldBuilder
Attributes
Implements

Examples

The following example illustrates the use of the FieldBuilder class.

using System;
using System.Reflection;
using System.Reflection.Emit;

public class FieldBuilder_Sample
{
   private static Type CreateType()
   {
      // Create an assembly.
      AssemblyName assemName = new AssemblyName();
      assemName.Name = "DynamicAssembly";
      AssemblyBuilder assemBuilder =
                     AssemblyBuilder.DefineDynamicAssembly(assemName, AssemblyBuilderAccess.Run);
      // Create a dynamic module in Dynamic Assembly.
      ModuleBuilder modBuilder = assemBuilder.DefineDynamicModule("DynamicModule");
      // Define a public class named "DynamicClass" in the assembly.
      TypeBuilder typBuilder = modBuilder.DefineType("DynamicClass", TypeAttributes.Public);

      // Define a private String field named "DynamicField" in the type.
      FieldBuilder fldBuilder = typBuilder.DefineField("DynamicField",
          typeof(string), FieldAttributes.Private | FieldAttributes.Static);
      // Create the constructor.
      Type[] constructorArgs = { typeof(String) };
      ConstructorBuilder constructor = typBuilder.DefineConstructor(
         MethodAttributes.Public, CallingConventions.Standard, constructorArgs);
      ILGenerator constructorIL = constructor.GetILGenerator();
      constructorIL.Emit(OpCodes.Ldarg_0);
      ConstructorInfo superConstructor = typeof(Object).GetConstructor(new Type[0]);
      constructorIL.Emit(OpCodes.Call, superConstructor);
      constructorIL.Emit(OpCodes.Ldarg_0);
      constructorIL.Emit(OpCodes.Ldarg_1);
      constructorIL.Emit(OpCodes.Stfld, fldBuilder);
      constructorIL.Emit(OpCodes.Ret);

      // Create the DynamicMethod method.
      MethodBuilder methBuilder= typBuilder.DefineMethod("DynamicMethod",
                           MethodAttributes.Public,typeof(String),null);
      ILGenerator methodIL = methBuilder.GetILGenerator();
      methodIL.Emit(OpCodes.Ldarg_0);
      methodIL.Emit(OpCodes.Ldfld, fldBuilder);
      methodIL.Emit(OpCodes.Ret);

      Console.WriteLine($"Name               : {fldBuilder.Name}");
      Console.WriteLine($"DeclaringType      : {fldBuilder.DeclaringType}");
      Console.WriteLine($"Type               : {fldBuilder.FieldType}");
      return typBuilder.CreateType();
   }

   public static void Main()
   {
      Type dynType = CreateType();
      try
      {
         // Create an instance of the "HelloWorld" class.
         Object helloWorld = Activator.CreateInstance(dynType, new Object[] { "HelloWorld" });
         // Invoke the "DynamicMethod" method of the "DynamicClass" class.
         Object obj  = dynType.InvokeMember("DynamicMethod",
                        BindingFlags.InvokeMethod, null, helloWorld, null);
         Console.WriteLine($"DynamicClass.DynamicMethod returned: \"{obj}\"");
      }
      catch(MethodAccessException e)
      {
         Console.WriteLine($"{e.GetType().Name}: {e.Message}");
      }
  }
}
Imports System.Reflection
Imports System.Reflection.Emit

Public Module FieldBuilder_Sample
   Private Function CreateType() As Type
      ' Create an assembly.
      Dim assemName As New AssemblyName()
      assemName.Name = "DynamicAssembly"
      Dim assemBuilder As AssemblyBuilder = AssemblyBuilder.DefineDynamicAssembly(assemName,
                                                AssemblyBuilderAccess.Run)
      ' Create a dynamic module in Dynamic Assembly.
      Dim modBuilder As ModuleBuilder = assemBuilder.DefineDynamicModule("DynamicModule")
      ' Define a public class named "DynamicClass" in the assembly.
      Dim typBuilder As TypeBuilder = modBuilder.DefineType("DynamicClass", 
                                          TypeAttributes.Public)
      ' Define a private String field named "DynamicField" in the type.
      Dim fldBuilder As FieldBuilder = typBuilder.DefineField("DynamicField",
                  GetType(String), FieldAttributes.Private Or FieldAttributes.Static)
      ' Create the constructor.
      Dim constructorArgs As Type() = {GetType(String)}
      Dim constructor As ConstructorBuilder = 
                  typBuilder.DefineConstructor(MethodAttributes.Public, 
                           CallingConventions.Standard, constructorArgs)
      Dim constructorIL As ILGenerator = constructor.GetILGenerator()
      constructorIL.Emit(OpCodes.Ldarg_0)
      Dim superConstructor As ConstructorInfo = GetType(Object).GetConstructor(New Type() {})
      constructorIL.Emit(OpCodes.Call, superConstructor)
      constructorIL.Emit(OpCodes.Ldarg_0)
      constructorIL.Emit(OpCodes.Ldarg_1)
      constructorIL.Emit(OpCodes.Stfld, fldBuilder)
      constructorIL.Emit(OpCodes.Ret)

      ' Create the DynamicMethod method.
      Dim methBuilder As MethodBuilder = typBuilder.DefineMethod("DynamicMethod", 
                        MethodAttributes.Public, GetType(String), Nothing)
      Dim methodIL As ILGenerator = methBuilder.GetILGenerator()
      methodIL.Emit(OpCodes.Ldarg_0)
      methodIL.Emit(OpCodes.Ldfld, fldBuilder)
      methodIL.Emit(OpCodes.Ret)

      Console.WriteLine($"Name               : {fldBuilder.Name}")
      Console.WriteLine($"DeclaringType      : {fldBuilder.DeclaringType}")
      Console.WriteLine($"Type               : {fldBuilder.FieldType}")
      Return typBuilder.CreateType()
   End Function 

   Public Sub Main()
      Dim dynType As Type = CreateType()
      Try  
        ' Create an instance of the "HelloWorld" class.
         Dim helloWorld As Object = Activator.CreateInstance(dynType, New Object() {"HelloWorld"})
         ' Invoke the "DynamicMethod" method of the "DynamicClass" class.
         Dim obj As Object = dynType.InvokeMember("DynamicMethod", 
                  BindingFlags.InvokeMethod, Nothing, helloWorld, Nothing)
         Console.WriteLine($"DynamicClass.DynamicMethod returned: ""{obj}""")
      Catch e As MethodAccessException
            Console.WriteLine($"{e.GetType().Name}: {e.Message}")
      End Try
   End Sub 
End Module

Remarks

Get an instance of FieldBuilder by calling DefineField, DefineInitializedData, or DefineUninitializedData.

Note

The SetValue method is currently not supported. As a workaround, retrieve the FieldInfo by reflecting on the finished type and call SetValue to set the value of the field.

Constructors

FieldBuilder()

Properties

Attributes

Indicates the attributes of this field. This property is read-only.

CustomAttributes

Gets a collection that contains this member's custom attributes.

(Inherited from MemberInfo)
DeclaringType

Indicates a reference to the Type object for the type that declares this field. This property is read-only.

FieldHandle

Indicates the internal metadata handle for this field. This property is read-only.

FieldHandle

Gets a RuntimeFieldHandle, which is a handle to the internal metadata representation of a field.

(Inherited from FieldInfo)
FieldType

Indicates the Type object that represents the type of this field. This property is read-only.

IsAssembly

Gets a value indicating whether the potential visibility of this field is described by Assembly; that is, the field is visible at most to other types in the same assembly, and is not visible to derived types outside the assembly.

(Inherited from FieldInfo)
IsCollectible

Gets a value that indicates whether this MemberInfo object is part of an assembly held in a collectible AssemblyLoadContext.

(Inherited from MemberInfo)
IsFamily

Gets a value indicating whether the visibility of this field is described by Family; that is, the field is visible only within its class and derived classes.

(Inherited from FieldInfo)
IsFamilyAndAssembly

Gets a value indicating whether the visibility of this field is described by FamANDAssem; that is, the field can be accessed from derived classes, but only if they are in the same assembly.

(Inherited from FieldInfo)
IsFamilyOrAssembly

Gets a value indicating whether the potential visibility of this field is described by FamORAssem; that is, the field can be accessed by derived classes wherever they are, and by classes in the same assembly.

(Inherited from FieldInfo)
IsInitOnly

Gets a value indicating whether the field can only be set in the body of the constructor.

(Inherited from FieldInfo)
IsLiteral

Gets a value indicating whether the value is written at compile time and cannot be changed.

(Inherited from FieldInfo)
IsNotSerialized

Gets a value indicating whether this field has the NotSerialized attribute.

(Inherited from FieldInfo)
IsPinvokeImpl

Gets a value indicating whether the corresponding PinvokeImpl attribute is set in FieldAttributes.

(Inherited from FieldInfo)
IsPrivate

Gets a value indicating whether the field is private.

(Inherited from FieldInfo)
IsPublic

Gets a value indicating whether the field is public.

(Inherited from FieldInfo)
IsSecurityCritical

Gets a value that indicates whether the current field is security-critical or security-safe-critical at the current trust level.

(Inherited from FieldInfo)
IsSecuritySafeCritical

Gets a value that indicates whether the current field is security-safe-critical at the current trust level.

(Inherited from FieldInfo)
IsSecurityTransparent

Gets a value that indicates whether the current field is transparent at the current trust level.

(Inherited from FieldInfo)
IsSpecialName

Gets a value indicating whether the corresponding SpecialName attribute is set in the FieldAttributes enumerator.

(Inherited from FieldInfo)
IsStatic

Gets a value indicating whether the field is static.

(Inherited from FieldInfo)
MemberType

Gets a MemberTypes value indicating that this member is a field.

(Inherited from FieldInfo)
MetadataToken

Gets a value that identifies a metadata element.

(Inherited from MemberInfo)
Module

Gets the module in which the type that contains this field is being defined.

Module

Gets the module in which the type that declares the member represented by the current MemberInfo is defined.

(Inherited from MemberInfo)
Name

Indicates the name of this field. This property is read-only.

ReflectedType

Indicates the reference to the Type object from which this object was obtained. This property is read-only.

ReflectedType

Gets the class object that was used to obtain this instance of MemberInfo.

(Inherited from MemberInfo)

Methods

Equals(Object)

Returns a value that indicates whether this instance is equal to a specified object.

(Inherited from FieldInfo)
GetCustomAttributes(Boolean)

Returns all the custom attributes defined for this field.

GetCustomAttributes(Boolean)

When overridden in a derived class, returns an array of all custom attributes applied to this member.

(Inherited from MemberInfo)
GetCustomAttributes(Type, Boolean)

Returns all the custom attributes defined for this field identified by the given type.

GetCustomAttributes(Type, Boolean)

When overridden in a derived class, returns an array of custom attributes applied to this member and identified by Type.

(Inherited from MemberInfo)
GetCustomAttributesData()

Returns a list of CustomAttributeData objects representing data about the attributes that have been applied to the target member.

(Inherited from MemberInfo)
GetHashCode()

Returns the hash code for this instance.

(Inherited from FieldInfo)
GetOptionalCustomModifiers()

Gets an array of types that identify the optional custom modifiers of the field.

(Inherited from FieldInfo)
GetRawConstantValue()

Returns a literal value associated with the field by a compiler.

(Inherited from FieldInfo)
GetRequiredCustomModifiers()

Gets an array of types that identify the required custom modifiers of the property.

(Inherited from FieldInfo)
GetToken()

Returns the token representing this field.

GetType()

Discovers the attributes of a class field and provides access to field metadata.

(Inherited from FieldInfo)
GetValue(Object)

Retrieves the value of the field supported by the given object.

GetValueDirect(TypedReference)

Returns the value of a field supported by a given object.

(Inherited from FieldInfo)
HasSameMetadataDefinitionAs(MemberInfo) (Inherited from MemberInfo)
IsDefined(Type, Boolean)

Indicates whether an attribute having the specified type is defined on a field.

IsDefined(Type, Boolean)

When overridden in a derived class, indicates whether one or more attributes of the specified type or of its derived types is applied to this member.

(Inherited from MemberInfo)
MemberwiseClone()

Creates a shallow copy of the current Object.

(Inherited from Object)
SetConstant(Object)

Sets the default value of this field.

SetCustomAttribute(ConstructorInfo, Byte[])

Sets a custom attribute using a specified custom attribute blob.

SetCustomAttribute(CustomAttributeBuilder)

Sets a custom attribute using a custom attribute builder.

SetMarshal(UnmanagedMarshal)
Obsolete.
Obsolete.

Describes the native marshaling of the field.

SetOffset(Int32)

Specifies the field layout.

SetValue(Object, Object)

Sets the value of the field supported by the given object.

(Inherited from FieldInfo)
SetValue(Object, Object, BindingFlags, Binder, CultureInfo)

Sets the value of the field supported by the given object.

SetValue(Object, Object, BindingFlags, Binder, CultureInfo)

When overridden in a derived class, sets the value of the field supported by the given object.

(Inherited from FieldInfo)
SetValueDirect(TypedReference, Object)

Sets the value of the field supported by the given object.

(Inherited from FieldInfo)
ToString()

Returns a string that represents the current object.

(Inherited from Object)

Explicit Interface Implementations

_FieldBuilder.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.

_FieldBuilder.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can then be used to get the type information for an interface.

_FieldBuilder.GetTypeInfoCount(UInt32)

Retrieves the number of type information interfaces that an object provides (either 0 or 1).

_FieldBuilder.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.

_FieldInfo.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.

(Inherited from FieldInfo)
_FieldInfo.GetType()

Gets a Type object representing the FieldInfo type.

(Inherited from FieldInfo)
_FieldInfo.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can then be used to get the type information for an interface.

(Inherited from FieldInfo)
_FieldInfo.GetTypeInfoCount(UInt32)

Retrieves the number of type information interfaces that an object provides (either 0 or 1).

(Inherited from FieldInfo)
_FieldInfo.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.

(Inherited from FieldInfo)
_MemberInfo.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

Maps a set of names to a corresponding set of dispatch identifiers.

(Inherited from MemberInfo)
_MemberInfo.GetType()

Gets a Type object representing the MemberInfo class.

(Inherited from MemberInfo)
_MemberInfo.GetTypeInfo(UInt32, UInt32, IntPtr)

Retrieves the type information for an object, which can then be used to get the type information for an interface.

(Inherited from MemberInfo)
_MemberInfo.GetTypeInfoCount(UInt32)

Retrieves the number of type information interfaces that an object provides (either 0 or 1).

(Inherited from MemberInfo)
_MemberInfo.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

Provides access to properties and methods exposed by an object.

(Inherited from MemberInfo)
ICustomAttributeProvider.GetCustomAttributes(Boolean)

Returns an array of all of the custom attributes defined on this member, excluding named attributes, or an empty array if there are no custom attributes.

(Inherited from MemberInfo)
ICustomAttributeProvider.GetCustomAttributes(Type, Boolean)

Returns an array of custom attributes defined on this member, identified by type, or an empty array if there are no custom attributes of that type.

(Inherited from MemberInfo)
ICustomAttributeProvider.IsDefined(Type, Boolean)

Indicates whether one or more instance of attributeType is defined on this member.

(Inherited from MemberInfo)

Extension Methods

GetCustomAttribute(MemberInfo, Type)

Retrieves a custom attribute of a specified type that is applied to a specified member.

GetCustomAttribute(MemberInfo, Type, Boolean)

Retrieves a custom attribute of a specified type that is applied to a specified member, and optionally inspects the ancestors of that member.

GetCustomAttribute<T>(MemberInfo)

Retrieves a custom attribute of a specified type that is applied to a specified member.

GetCustomAttribute<T>(MemberInfo, Boolean)

Retrieves a custom attribute of a specified type that is applied to a specified member, and optionally inspects the ancestors of that member.

GetCustomAttributes(MemberInfo)

Retrieves a collection of custom attributes that are applied to a specified member.

GetCustomAttributes(MemberInfo, Boolean)

Retrieves a collection of custom attributes that are applied to a specified member, and optionally inspects the ancestors of that member.

GetCustomAttributes(MemberInfo, Type)

Retrieves a collection of custom attributes of a specified type that are applied to a specified member.

GetCustomAttributes(MemberInfo, Type, Boolean)

Retrieves a collection of custom attributes of a specified type that are applied to a specified member, and optionally inspects the ancestors of that member.

GetCustomAttributes<T>(MemberInfo)

Retrieves a collection of custom attributes of a specified type that are applied to a specified member.

GetCustomAttributes<T>(MemberInfo, Boolean)

Retrieves a collection of custom attributes of a specified type that are applied to a specified member, and optionally inspects the ancestors of that member.

IsDefined(MemberInfo, Type)

Indicates whether custom attributes of a specified type are applied to a specified member.

IsDefined(MemberInfo, Type, Boolean)

Indicates whether custom attributes of a specified type are applied to a specified member, and, optionally, applied to its ancestors.

GetMetadataToken(MemberInfo)

Gets a metadata token for the given member, if available.

HasMetadataToken(MemberInfo)

Returns a value that indicates whether a metadata token is available for the specified member.

Applies to