PropertyInfo.CanWrite Eigenschaft

Definition

Namespace:

System.Reflection

Assembly:

System.Runtime.dll

Quelle:

PropertyInfo.cs

Ruft einen Wert ab, der angibt, ob in die Eigenschaft geschrieben werden kann.

public:
 abstract property bool CanWrite { bool get(); };

public abstract bool CanWrite { get; }

member this.CanWrite : bool

Public MustOverride ReadOnly Property CanWrite As Boolean

Eigenschaftswert

Boolean

true, wenn in diese Eigenschaft geschrieben werden kann, andernfalls false.

Beispiele

Im folgenden Beispiel werden zwei Eigenschaften definiert. Die erste Eigenschaft ist beschreibbar, und die CanWrite -Eigenschaft ist true. Die zweite Eigenschaft ist nicht beschreibbar (es gibt keinen set Accessor), und die CanWrite -Eigenschaft ist false.

using namespace System;
using namespace System::Reflection;

// Define one writable property and one not writable.
public ref class Mypropertya
{
private:
   String^ caption;

public:
   Mypropertya()
      : caption( "A Default caption" )
   {}


   property String^ Caption 
   {
      String^ get()
      {
         return caption;
      }

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

   }

};

public ref class Mypropertyb
{
private:
   String^ caption;

public:
   Mypropertyb()
      : caption( "B Default caption" )
   {}


   property String^ Caption 
   {
      String^ get()
      {
         return caption;
      }

   }

};

int main()
{
   Console::WriteLine( "\nReflection.PropertyInfo" );
   
   // Define two properties.
   Mypropertya^ mypropertya = gcnew Mypropertya;
   Mypropertyb^ mypropertyb = gcnew Mypropertyb;
   
   // Read and display the property.
   Console::Write( "\nMypropertya->Caption = {0}", mypropertya->Caption );
   Console::Write( "\nMypropertyb->Caption = {0}", mypropertyb->Caption );
   
   // Write to the property.
   mypropertya->Caption = "A- No Change";
   
   // Mypropertyb.Caption cannot be written to because
   // there is no set accessor.
   // Read and display the property.
   Console::Write( "\nMypropertya->Caption = {0}", mypropertya->Caption );
   Console::Write( "\nMypropertyb->Caption = {0}", mypropertyb->Caption );
   
   // Get the type and PropertyInfo.
   Type^ MyTypea = Type::GetType( "Mypropertya" );
   PropertyInfo^ Mypropertyinfoa = MyTypea->GetProperty( "Caption" );
   Type^ MyTypeb = Type::GetType( "Mypropertyb" );
   PropertyInfo^ Mypropertyinfob = MyTypeb->GetProperty( "Caption" );
   
   // Get and display the CanWrite property.
   Console::Write( "\nCanWrite a - {0}", Mypropertyinfoa->CanWrite );
   Console::Write( "\nCanWrite b - {0}", Mypropertyinfob->CanWrite );
   return 0;
}

using System;
using System.Reflection;

 // Define one writable property and one not writable.
public class Mypropertya
{
    private string caption = "A Default caption";
    public string Caption
    {
        get{return caption;}
        set {if(caption!=value) {caption = value;}
        }
    }
}
public class Mypropertyb
{
    private string caption = "B Default caption";
    public string Caption
    {
        get{return caption;}
    }
}

class Mypropertyinfo
{
    public static int Main()
    {
        Console.WriteLine("\nReflection.PropertyInfo");

        // Define two properties.
        Mypropertya Mypropertya = new Mypropertya();
        Mypropertyb Mypropertyb = new Mypropertyb();

        // Read and display the property.
        Console.Write("\nMypropertya.Caption = " + Mypropertya.Caption);
        Console.Write("\nMypropertyb.Caption = " + Mypropertyb.Caption);

        // Write to the property.
        Mypropertya.Caption = "A- No Change";
        // Mypropertyb.Caption cannot be written to because
        // there is no set accessor.

        // Read and display the property.
        Console.Write("\nMypropertya.Caption = " + Mypropertya.Caption);
        Console.Write ("\nMypropertyb.Caption = " + Mypropertyb.Caption);

        // Get the type and PropertyInfo.
        Type MyTypea = Type.GetType("Mypropertya");
        PropertyInfo Mypropertyinfoa = MyTypea.GetProperty("Caption");
        Type MyTypeb = Type.GetType("Mypropertyb");
        PropertyInfo Mypropertyinfob = MyTypeb.GetProperty("Caption");

        // Get and display the CanWrite property.

        Console.Write("\nCanWrite a - " + Mypropertyinfoa.CanWrite);

        Console.Write("\nCanWrite b - " + Mypropertyinfob.CanWrite);

        return 0;
    }
}

Imports System.Reflection

' Define one writable property and one not writable.
Public Class Mypropertya
    Private myCaption As String = "A Default caption"

    Public Property Caption() As String
        Get
            Return myCaption
        End Get
        Set(ByVal Value As String)
            If myCaption <> value Then
                myCaption = value
            End If
        End Set
    End Property
End Class

Public Class Mypropertyb
    Private myCaption As String = "B Default caption"

    Public ReadOnly Property Caption() As String
        Get
            Return myCaption
        End Get
    End Property
End Class

Class Mypropertyinfo

    Public Shared Function Main() As Integer
        Console.WriteLine(ControlChars.CrLf & "Reflection.PropertyInfo")

        ' Define two properties.
        Dim Mypropertya As New Mypropertya()
        Dim Mypropertyb As New Mypropertyb()

        ' Read and display the property.
        Console.Write(ControlChars.CrLf & "Mypropertya.Caption = " & _
           Mypropertya.Caption)
        Console.Write(ControlChars.CrLf & "Mypropertyb.Caption = " & _
           Mypropertyb.Caption)

        ' Write to the property.
        Mypropertya.Caption = "A- No Change"
        ' Mypropertyb.Caption cannot be written to because
        ' there is no set accessor.
        ' Read and display the property.
        Console.Write(ControlChars.CrLf & "Mypropertya.Caption = " & _
           Mypropertya.Caption)
        Console.Write(ControlChars.CrLf & "Mypropertyb.Caption = " & _
           Mypropertyb.Caption)

        ' Get the type and PropertyInfo.
        Dim MyTypea As Type = Type.GetType("Mypropertya")
        Dim Mypropertyinfoa As PropertyInfo = MyTypea.GetProperty("Caption")
        Dim MyTypeb As Type = Type.GetType("Mypropertyb")
        Dim Mypropertyinfob As PropertyInfo = MyTypeb.GetProperty("Caption")

        ' Get and display the CanWrite property.
        Console.Write(ControlChars.CrLf & "CanWrite a - " & _
           Mypropertyinfoa.CanWrite)

        Console.Write(ControlChars.CrLf & "CanWrite b - " & _
           Mypropertyinfob.CanWrite)

        Return 0
    End Function
End Class

Hinweise

CanWrite gibt zurück true , wenn die Eigenschaft über einen set Accessor verfügt, auch wenn der Accessor privateist, internal (oder Friend in Visual Basic) oder protected. Wenn die -Eigenschaft keinen set Accessor aufweist, gibt die -Methode zurück false.

So rufen Sie den Wert der CanWrite Eigenschaft ab:

1. Ruft das Type Objekt des Typs ab, der die -Eigenschaft enthält.

2. Rufen Sie auf Type.GetProperty , um das PropertyInfo Objekt abzurufen, das die -Eigenschaft darstellt.

3. Rufen Sie den Wert der -Eigenschaft ab CanWrite .