Expression.Empty Metode

Definisi

Ruang nama:

System.Linq.Expressions

Rakitan:

System.Linq.Expressions.dll

Sumber:

DefaultExpression.cs

Membuat ekspresi kosong yang memiliki Void jenis.

public:
 static System::Linq::Expressions::DefaultExpression ^ Empty();

public static System.Linq.Expressions.DefaultExpression Empty ();

static member Empty : unit -> System.Linq.Expressions.DefaultExpression

Public Shared Function Empty () As DefaultExpression

Mengembalikan

DefaultExpression

DefaultExpression yang memiliki NodeType properti yang sama dengan Default dan Type properti diatur ke Void.

Contoh

Contoh kode berikut menunjukkan cara membuat ekspresi kosong dan menambahkannya ke ekspresi blok.

// Add the following directive to your file:
// using System.Linq.Expressions;

// This statement creates an empty expression.
DefaultExpression emptyExpr = Expression.Empty();

// The empty expression can be used where an expression is expected, but no action is desired.
// For example, you can use the empty expression as the last expression in the block expression.
// In this case the block expression's return value is void.
var emptyBlock = Expression.Block(emptyExpr);

' Add the following directive to your file:
' Imports System.Linq.Expressions 

' This statement creates an empty expression.
Dim emptyExpr As DefaultExpression = Expression.Empty()

' An empty expression can be used where an expression is expected but no action is desired.
' For example, you can use an empty expression as the last expression in a block expression.
' In this case, the block expression's return value is void.
Dim emptyBlock = Expression.Block(emptyExpr)

Keterangan

Ekspresi kosong dapat digunakan di mana ekspresi diharapkan tetapi tidak ada tindakan yang diinginkan. Misalnya, Anda dapat menggunakan ekspresi kosong sebagai ekspresi terakhir dalam ekspresi blok. Dalam hal ini, nilai pengembalian ekspresi blok batal.