Enumerable.AsEnumerable<TSource>(IEnumerable<TSource>) Método

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<TSource> ^ AsEnumerable(System::Collections::Generic::IEnumerable<TSource> ^ source);

public static System.Collections.Generic.IEnumerable<TSource> AsEnumerable<TSource> (this System.Collections.Generic.IEnumerable<TSource> source);

static member AsEnumerable : seq<'Source> -> seq<'Source>

<Extension()>
Public Function AsEnumerable(Of TSource) (source As IEnumerable(Of TSource)) As IEnumerable(Of TSource)

Parámetros de tipo

Parámetros

Devoluciones

IEnumerable<TSource>

Secuencia de entrada tipada como IEnumerable<T>.The input sequence typed as IEnumerable<T>.

Ejemplos

En el ejemplo de código siguiente se muestra cómo utilizar AsEnumerable<TSource>(IEnumerable<TSource>) para ocultar el método personalizado de un tipo Where cuando se desea la implementación del operador de consulta estándar.The following code example demonstrates how to use AsEnumerable<TSource>(IEnumerable<TSource>) to hide a type's custom Where method when the standard query operator implementation is desired.

// Custom class.
class Clump<T> : List<T>
{
    // Custom implementation of Where().
    public IEnumerable<T> Where(Func<T, bool> predicate)
    {
        Console.WriteLine("In Clump's implementation of Where().");
        return Enumerable.Where(this, predicate);
    }
}

static void AsEnumerableEx1()
{
    // Create a new Clump<T> object.
    Clump<string> fruitClump =
        new Clump<string> { "apple", "passionfruit", "banana",
            "mango", "orange", "blueberry", "grape", "strawberry" };

    // First call to Where():
    // Call Clump's Where() method with a predicate.
    IEnumerable<string> query1 =
        fruitClump.Where(fruit => fruit.Contains("o"));

    Console.WriteLine("query1 has been created.\n");

    // Second call to Where():
    // First call AsEnumerable() to hide Clump's Where() method and thereby
    // force System.Linq.Enumerable's Where() method to be called.
    IEnumerable<string> query2 =
        fruitClump.AsEnumerable().Where(fruit => fruit.Contains("o"));

    // Display the output.
    Console.WriteLine("query2 has been created.");
}

// This code produces the following output:
//
// In Clump's implementation of Where().
// query1 has been created.
//
// query2 has been created.

Dim output As New System.Text.StringBuilder

' A custom class.
Class Clump(Of T)
    Inherits List(Of T)

    ' Constructor.
    Public Sub New(ByVal collection As IEnumerable(Of T))
        MyBase.New(collection)
    End Sub

    ' Custom implementation of Where().
    Function Where(ByVal predicate As Func(Of T, Boolean)) As IEnumerable(Of T)
        output.AppendLine("In Clump's implementation of Where().")
        Return Enumerable.Where(Me, predicate)
    End Function
End Class

Sub AsEnumerableEx1()
    ' Create a new Clump(Of T) object.
    Dim fruitClump As New Clump(Of String)(New String() _
                                       {"apple", "passionfruit", "banana",
                                        "mango", "orange", "blueberry",
                                        "grape", "strawberry"})

    ' First call to Where():
    ' Call Clump's Where() method with a predicate.
    Dim query1 As IEnumerable(Of String) =
    fruitClump.Where(Function(fruit) fruit.Contains("o"))
    output.AppendLine("query1 has been created." & vbCrLf)

    ' Second call to Where():
    ' First call AsEnumerable() to hide Clump's Where() method and thereby
    ' force System.Linq.Enumerable's Where() method to be called.
    Dim query2 As IEnumerable(Of String) =
    fruitClump.AsEnumerable().Where(Function(fruit) fruit.Contains("o"))
    output.AppendLine("query2 has been created.")

    ' Display the output.
    Console.WriteLine(output.ToString())
End Sub

' This code produces the following output:
'
' In Clump's implementation of Where().
' query1 has been created.
'
' query2 has been created.

Comentarios

El AsEnumerable<TSource>(IEnumerable<TSource>) método no tiene ningún efecto distinto de cambiar el tipo en tiempo de compilación de source de un tipo que IEnumerable<T> se implementa en IEnumerable<T> sí mismo.The AsEnumerable<TSource>(IEnumerable<TSource>) method has no effect other than to change the compile-time type of source from a type that implements IEnumerable<T> to IEnumerable<T> itself.

AsEnumerable<TSource>(IEnumerable<TSource>) se puede usar para elegir entre implementaciones de consulta cuando una secuencia implementa, IEnumerable<T> pero también tiene un conjunto diferente de métodos de consulta públicos disponibles.AsEnumerable<TSource>(IEnumerable<TSource>) can be used to choose between query implementations when a sequence implements IEnumerable<T> but also has a different set of public query methods available. Por ejemplo, dada una clase genérica Table que implementa IEnumerable<T> y tiene sus propios métodos, como Where , Select y SelectMany , una llamada a Where invocaría al Where método público de Table .For example, given a generic class Table that implements IEnumerable<T> and has its own methods such as Where, Select, and SelectMany, a call to Where would invoke the public Where method of Table. Un Table tipo que representa una tabla de base de datos podría tener un Where método que toma el argumento de predicado como un árbol de expresión y convierte el árbol en SQL para la ejecución remota.A Table type that represents a database table could have a Where method that takes the predicate argument as an expression tree and converts the tree to SQL for remote execution. Si no se desea ejecutar de forma remota, por ejemplo, porque el predicado invoca un método local, el AsEnumerable método se puede utilizar para ocultar los métodos personalizados y, en su lugar, hacer que los operadores de consulta estándar estén disponibles.If remote execution is not desired, for example because the predicate invokes a local method, the AsEnumerable method can be used to hide the custom methods and instead make the standard query operators available.

Se aplica a