FieldInfo.IsInitOnly Propiedad

Definición

Espacio de nombres:

System.Reflection

Ensamblado:

System.Runtime.dll

Source:

FieldInfo.cs

Obtiene un valor que indica si el campo sólo se puede establecer en el cuerpo del constructor.

public:
 property bool IsInitOnly { bool get(); };

public bool IsInitOnly { get; }

member this.IsInitOnly : bool

Public ReadOnly Property IsInitOnly As Boolean

Valor de propiedad

Boolean

Es true si el campo tiene establecido el atributo InitOnly; en caso contrario, es false.

Ejemplos

En el ejemplo siguiente, se crean dos campos. El segundo campo es de solo lectura, sin descriptor de acceso set y IsInitOnly se establece en true.

using namespace System;
using namespace System::Reflection;

//Make two fields, one public and one read-only.
public ref class Myfielda
{
public:
   String^ field;
   Myfielda()
      : field( "A - public field" )
   {}


   property String^ Field 
   {
      String^ get()
      {
         return field;
      }

      void set( String^ value )
      {
         if ( field != value )
         {
            field = value;
         }
      }

   }

};

public ref class Myfieldb
{
private:
   String^ const field;

public:
   Myfieldb()
      : field( "B - readonly field" )
   {}


   property String^ Field 
   {
      String^ get()
      {
         return field;
      }

   }

};

int main()
{
   Console::WriteLine( "\nReflection.FieldInfo" );
   Myfielda^ myfielda = gcnew Myfielda;
   Myfieldb^ myfieldb = gcnew Myfieldb;
   
   //Get the Type and FieldInfo.
   Type^ MyTypea = Type::GetType( "Myfielda" );
   FieldInfo^ Myfieldinfoa = MyTypea->GetField( "field", static_cast<BindingFlags>(BindingFlags::Public | BindingFlags::Instance) );
   Type^ MyTypeb = Type::GetType( "Myfieldb" );
   FieldInfo^ Myfieldinfob = MyTypeb->GetField( "field", static_cast<BindingFlags>(BindingFlags::NonPublic | BindingFlags::Instance) );
   
   //Modify the fields.
   //Note that Myfieldb is not modified, as it is
   //read-only (IsInitOnly is True).
   myfielda->field = "A- modified";
   
   //Myfieldb.field = "B- modified";
   //For the first field, get and display the name, field, and IsInitOnly state.
   Console::Write( "\n{0} - {1}, IsInitOnly = {2} ", MyTypea->FullName, Myfieldinfoa->GetValue( myfielda ), Myfieldinfoa->IsInitOnly );
   
   //For the second field get and display the name, field, and IsInitOnly state.
   Console::Write( "\n{0} - {1}, IsInitOnly = {2} ", MyTypeb->FullName, Myfieldinfob->GetValue( myfieldb ), Myfieldinfob->IsInitOnly );
   return 0;
}

using System;
using System.Reflection;

//Make two fields, one public and one read-only.
public class Myfielda
{
    public string field = "A - public modifiable field";
}
public class Myfieldb
{
    public readonly string field = "B - readonly field";
}

public class Myfieldinfo
{
    public static int Main()
    {
        Console.WriteLine("\nReflection.FieldInfo");
        Myfielda Myfielda = new Myfielda();
        Myfieldb Myfieldb = new Myfieldb();

        //Get the Type and FieldInfo.
        Type MyTypea = typeof(Myfielda);
        FieldInfo Myfieldinfoa = MyTypea.GetField("field",
            BindingFlags.Public | BindingFlags.Instance);
        Type MyTypeb = typeof(Myfieldb);
        FieldInfo Myfieldinfob = MyTypeb.GetField("field",
            BindingFlags.Public | BindingFlags.Instance);

        //Modify the fields.
        //Note that Myfieldb is not modified, as it is
        //read-only (IsInitOnly is True).
        Myfielda.field = "A - modified";
        //Myfieldb.field = "B - modified";

        //For the first field, get and display the name, field, and IsInitOnly state.
        Console.Write("\n{0} - {1}, IsInitOnly = {2} ",
            MyTypea.FullName,
            Myfieldinfoa.GetValue(Myfielda),
            Myfieldinfoa.IsInitOnly);

        //For the second field get and display the name, field, and IsInitOnly state.
        Console.Write("\n{0} - {1}, IsInitOnly = {2} ",
            MyTypeb.FullName,
            Myfieldinfob.GetValue(Myfieldb),
            Myfieldinfob.IsInitOnly);

        return 0;
    }
}

Imports System.Reflection

'Make two fields, one public and one read-only.
Public Class Myfielda
    Public field As String = "A - public modifiable field"
End Class

Public Class Myfieldb
    Public ReadOnly field As String = "B - readonly field"
End Class

Public Class Myfieldinfo
    Public Shared Function Main() As Integer
        Console.WriteLine("Reflection.FieldInfo")
        Console.WriteLine()
        Dim Myfielda As New Myfielda()
        Dim Myfieldb As New Myfieldb()

        'Get the Type and FieldInfo.
        Dim MyTypea As Type = GetType(Myfielda)
        Dim Myfieldinfoa As FieldInfo = MyTypea.GetField("field", _
            BindingFlags.Public Or BindingFlags.Instance)
        Dim MyTypeb As Type = GetType(Myfieldb)
        Dim Myfieldinfob As FieldInfo = MyTypeb.GetField("field", _
            BindingFlags.Public Or BindingFlags.Instance)

        'Modify the fields.
        'Note that Myfieldb is not modified, as it is
        'read-only (IsInitOnly is True).
        Myfielda.field = "A - modified"
        'For the first field, get and display the name, field, and IsInitOnly state.
        Console.WriteLine("{0} - {1}, IsInitOnly = {2} ", MyTypea.FullName, _
            Myfieldinfoa.GetValue(Myfielda), Myfieldinfoa.IsInitOnly)
        'For the second field get and display the name, field, and IsInitOnly state.
        Console.WriteLine("{0} - {1}, IsInitOnly = {2} ", MyTypeb.FullName, _
            Myfieldinfob.GetValue(Myfieldb), Myfieldinfob.IsInitOnly)

        Return 0
    End Function 'Main
End Class

Este código genera el siguiente resultado:

Reflection.FieldInfo

Myfielda - A- modified, IsInitOnly = False

Myfieldb - B readonly field, IsInitOnly = True

Comentarios

Si el valor devuelto es true, el campo solo se puede inicializar y es de solo lectura a partir de entonces.

Para obtener la IsInitOnly propiedad , obtenga primero la clase Type. TypeEn , obtenga .FieldInfo En , FieldInfoobtenga la IsInitOnly propiedad . Para acceder a un campo no público, combine BindingFlags.NonPublic con o con o con BindingFlags.Static y BindingFlags.Instance en el GetField método .

La IsInitOnly propiedad se establece cuando se establece el FieldAttributes.InitOnly atributo .

Consulte también

• FieldAttributes
• GetField(String, BindingFlags)
• Type