FieldInfo.IsInitOnly Vlastnost

Definice

Obor názvů:

System.Reflection

Sestavení:

netstandard.dll, System.Runtime.dll

Zdroj:

FieldInfo.cs

Získá hodnotu určující, zda pole lze nastavit pouze v těle konstruktoru.

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

public bool IsInitOnly { get; }

member this.IsInitOnly : bool

Public ReadOnly Property IsInitOnly As Boolean

Hodnota vlastnosti

Boolean

true pokud má pole nastaven atribut InitOnly ; jinak , false.

Příklady

V následujícím příkladu se vytvoří dvě pole. Druhé pole je jen pro čtení, nemá žádné nastavení přístupového objektu a IsInitOnly je nastaveno na true.

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

Tento kód vytvoří následující výstup:

Reflection.FieldInfo

Myfielda - A- modified, IsInitOnly = False

Myfieldb - B readonly field, IsInitOnly = True

Poznámky

Pokud je truevrácená hodnota, může být pole inicializováno pouze pro čtení.

Pokud chcete získat IsInitOnly vlastnost, nejprve získejte třídu Type. Z Typezískejte FieldInfo. Z objektu FieldInfo, získejte IsInitOnly vlastnost. Pokud chcete získat přístup k neveřejným poli, zkombinujte BindingFlags.NonPublic ho BindingFlags.StaticBindingFlags.Instance s metodou GetField nebo s oběma způsoby.

Vlastnost IsInitOnly je nastavena při nastavení atributu FieldAttributes.InitOnly .

Viz také

• FieldAttributes
• GetField(String, BindingFlags)
• Type