Object.MemberwiseClone Object.MemberwiseClone Object.MemberwiseClone Object.MemberwiseClone Method

Definition

Crea una copia superficial del Object actual. Creates a shallow copy of the current Object.

protected:
 System::Object ^ MemberwiseClone();
protected object MemberwiseClone ();
member this.MemberwiseClone : unit -> obj
Protected Function MemberwiseClone () As Object

Returns

Copia superficial del Object actual. A shallow copy of the current Object.

Examples

El ejemplo siguiente ilustra la MemberwiseClone método.The following example illustrates the MemberwiseClone method. Define un ShallowCopy método al que llama el MemberwiseClone método para realizar una operación de copia superficial de un Person objeto.It defines a ShallowCopy method that calls the MemberwiseClone method to perform a shallow copy operation on a Person object. También define un DeepCopy método que realiza una operación de copia en profundidad en un Person objeto.It also defines a DeepCopy method that performs a deep copy operation on a Person object.

using System;

public class IdInfo
{
    public int IdNumber;
    
    public IdInfo(int IdNumber)
    {
        this.IdNumber = IdNumber;
    }
}

public class Person 
{
    public int Age;
    public string Name;
    public IdInfo IdInfo;

    public Person ShallowCopy()
    {
       return (Person) this.MemberwiseClone();
    }

    public Person DeepCopy()
    {
       Person other = (Person) this.MemberwiseClone();
       other.IdInfo = new IdInfo(IdInfo.IdNumber);
       other.Name = String.Copy(Name);
       return other;
    }
}

public class Example
{
    public static void Main()
    {
        // Create an instance of Person and assign values to its fields.
        Person p1 = new Person();
        p1.Age = 42;
        p1.Name = "Sam";
        p1.IdInfo = new IdInfo(6565);

        // Perform a shallow copy of p1 and assign it to p2.
        Person p2 = p1.ShallowCopy();

        // Display values of p1, p2
        Console.WriteLine("Original values of p1 and p2:");
        Console.WriteLine("   p1 instance values: ");
        DisplayValues(p1);
        Console.WriteLine("   p2 instance values:");
        DisplayValues(p2);
        
        // Change the value of p1 properties and display the values of p1 and p2.
        p1.Age = 32;
        p1.Name = "Frank";
        p1.IdInfo.IdNumber = 7878;
        Console.WriteLine("\nValues of p1 and p2 after changes to p1:");
        Console.WriteLine("   p1 instance values: ");
        DisplayValues(p1);
        Console.WriteLine("   p2 instance values:");
        DisplayValues(p2);

        // Make a deep copy of p1 and assign it to p3.
        Person p3 = p1.DeepCopy();
        // Change the members of the p1 class to new values to show the deep copy.
        p1.Name = "George";
        p1.Age = 39;
        p1.IdInfo.IdNumber = 8641;
        Console.WriteLine("\nValues of p1 and p3 after changes to p1:");
        Console.WriteLine("   p1 instance values: ");
        DisplayValues(p1);
        Console.WriteLine("   p3 instance values:");
        DisplayValues(p3);
    }

    public static void DisplayValues(Person p)
    {
        Console.WriteLine("      Name: {0:s}, Age: {1:d}", p.Name, p.Age);
        Console.WriteLine("      Value: {0:d}", p.IdInfo.IdNumber);
    }
}
// The example displays the following output:
//       Original values of p1 and p2:
//          p1 instance values:
//             Name: Sam, Age: 42
//             Value: 6565
//          p2 instance values:
//             Name: Sam, Age: 42
//             Value: 6565
//       
//       Values of p1 and p2 after changes to p1:
//          p1 instance values:
//             Name: Frank, Age: 32
//             Value: 7878
//          p2 instance values:
//             Name: Sam, Age: 42
//             Value: 7878
//       
//       Values of p1 and p3 after changes to p1:
//          p1 instance values:
//             Name: George, Age: 39
//             Value: 8641
//          p3 instance values:
//             Name: Frank, Age: 32
//             Value: 7878
Public Class IdInfo
    Public IdNumber As Integer
    
    Public Sub New(IdNumber As Integer)
        Me.IdNumber = IdNumber
    End Sub
End Class

Public Class Person 
    Public Age As Integer
    Public Name As String
    Public IdInfo As IdInfo

    Public Function ShallowCopy() As Person
       Return DirectCast(Me.MemberwiseClone(), Person)
    End Function

    Public Function DeepCopy() As Person
       Dim other As Person = DirectCast(Me.MemberwiseClone(), Person) 
       other.IdInfo = New IdInfo(IdInfo.IdNumber)
       other.Name = String.Copy(Name)
       Return other
    End Function
End Class

Module Example
   Public Sub Main()
        ' Create an instance of Person and assign values to its fields.
        Dim p1 As New Person()
        p1.Age = 42
        p1.Name = "Sam"
        p1.IdInfo = New IdInfo(6565)

        ' Perform a shallow copy of p1 and assign it to p2.
        Dim p2 As Person = p1.ShallowCopy()

        ' Display values of p1, p2
        Console.WriteLine("Original values of p1 and p2:")
        Console.WriteLine("   p1 instance values: ")
        DisplayValues(p1)
        Console.WriteLine("   p2 instance values:")
        DisplayValues(p2)
        Console.WriteLine()
                
        ' Change the value of p1 properties and display the values of p1 and p2.
        p1.Age = 32
        p1.Name = "Frank"
        p1.IdInfo.IdNumber = 7878
        Console.WriteLine("Values of p1 and p2 after changes to p1:")
        Console.WriteLine("   p1 instance values: ")
        DisplayValues(p1)
        Console.WriteLine("   p2 instance values:")
        DisplayValues(p2)
        Console.WriteLine()
        
        ' Make a deep copy of p1 and assign it to p3.
        Dim p3 As Person = p1.DeepCopy()
        ' Change the members of the p1 class to new values to show the deep copy.
        p1.Name = "George"
        p1.Age = 39
        p1.IdInfo.IdNumber = 8641
        Console.WriteLine("Values of p1 and p3 after changes to p1:")
        Console.WriteLine("   p1 instance values: ")
        DisplayValues(p1)
        Console.WriteLine("   p3 instance values:")
        DisplayValues(p3)
   End Sub
   
    Public Sub DisplayValues(p As Person)
        Console.WriteLine("      Name: {0:s}, Age: {1:d}", p.Name, p.Age)
        Console.WriteLine("      Value: {0:d}", p.IdInfo.IdNumber)
    End Sub
End Module
' The example displays the following output:
'       Original values of m1 and m2:
'          m1 instance values:
'             Name: Sam, Age: 42
'             Value: 6565
'          m2 instance values:
'             Name: Sam, Age: 42
'             Value: 6565
'       
'       Values of m1 and m2 after changes to m1:
'          m1 instance values:
'             Name: Frank, Age: 32
'             Value: 7878
'          m2 instance values:
'             Name: Sam, Age: 42
'             Value: 7878
'       
'       Values of m1 and m3 after changes to m1:
'          m1 instance values:
'             Name: George, Age: 39
'             Value: 8641
'          m3 instance values:
'             Name: Frank, Age: 32
'             Value: 7878

En este ejemplo, el Person.IdInfo propiedad devuelve un IdInfo objeto.In this example, the Person.IdInfo property returns an IdInfo object. Como la salida muestra el ejemplo, cuando un Person se clona el objeto mediante una llamada a la MemberwiseClone método, clonado Person objeto es una copia independiente del objeto original, excepto que comparten el mismo Person.IdInfo referencia de objeto.As the output from the example shows, when a Person object is cloned by calling the MemberwiseClone method, the cloned Person object is an independent copy of the original object, except that they share the same Person.IdInfo object reference. Como resultado, modificar el clon Person.IdInfo propiedad cambia el objeto original Person.IdInfo propiedad.As a result, modifying the clone's Person.IdInfo property changes the original object's Person.IdInfo property. Por otro lado, cuando se realiza una operación de copia en profundidad, clonado Person objeto, incluida su Person.IdInfo propiedad, puede modificarse sin alterar el objeto original.On the other hand, when a deep copy operation is performed, the cloned Person object, including its Person.IdInfo property, can be modified without affecting the original object.

Remarks

El MemberwiseClone método crea una copia superficial creando un nuevo objeto y, a continuación, copiar los campos no estáticos del objeto actual en el nuevo objeto.The MemberwiseClone method creates a shallow copy by creating a new object, and then copying the nonstatic fields of the current object to the new object. Si un campo es un tipo de valor, se realiza una copia bit a bit del campo.If a field is a value type, a bit-by-bit copy of the field is performed. Si un campo es un tipo de referencia, se copia la referencia, pero el objeto que se hace referencia no; es por lo tanto, el objeto original y su clon hacen referencia al mismo objeto.If a field is a reference type, the reference is copied but the referred object is not; therefore, the original object and its clone refer to the same object.

Por ejemplo, considere la posibilidad de un objeto denominado X que hace referencia a objetos A y B. objeto B, a su vez, el objeto references C. Una copia superficial de X crea el nuevo objeto X2 que también hace referencia a objetos A y B. En cambio, una copia en profundidad de X crea un nuevo objeto X2 que hace referencia a los nuevos objetos A2 y B2, que son copias de la A y B. B2, a su vez, hace referencia al objeto nuevo C2, que es una copia de C. En el ejemplo se muestra la diferencia entre una operación de copia en profundidad y un poco.For example, consider an object called X that references objects A and B. Object B, in turn, references object C. A shallow copy of X creates new object X2 that also references objects A and B. In contrast, a deep copy of X creates a new object X2 that references the new objects A2 and B2, which are copies of A and B. B2, in turn, references the new object C2, which is a copy of C. The example illustrates the difference between a shallow and a deep copy operation.

Hay muchas formas para implementar una operación de copia en profundidad si realiza la operación de copia superficial del MemberwiseClone método no satisfacen sus necesidades.There are numerous ways to implement a deep copy operation if the shallow copy operation performed by the MemberwiseClone method does not meet your needs. Entre ellas se incluyen las siguientes:These include the following:

  • Llamar a un constructor de clase del objeto que se va a copiar para crear un segundo objeto con valores de propiedad tomados del primer objeto.Call a class constructor of the object to be copied to create a second object with property values taken from the first object. Se supone que los valores de un objeto completamente se definen mediante su constructor de clase.This assumes that the values of an object are entirely defined by its class constructor.

  • Llame a la MemberwiseClone método para crear una copia superficial de un objeto y, a continuación, asignar nuevos objetos cuyos valores son los mismos que el objeto original para las propiedades o campos cuyos valores son tipos de referencia.Call the MemberwiseClone method to create a shallow copy of an object, and then assign new objects whose values are the same as the original object to any properties or fields whose values are reference types. El DeepCopy método en el ejemplo muestra este enfoque.The DeepCopy method in the example illustrates this approach.

  • Serializar el objeto como deep copiado y, a continuación, restaurar los datos serializados en una variable de objeto diferente.Serialize the object to be deep copied, and then restore the serialized data to a different object variable.

  • Usar la reflexión para realizar la operación de copia en profundidad con la recursión.Use reflection with recursion to perform the deep copy operation.

Applies to