Expression.TypeAs(Expression, Type) Expression.TypeAs(Expression, Type) Expression.TypeAs(Expression, Type) Method

定義

名前空間:
System.Linq.Expressions System.Linq.Expressions System.Linq.Expressions
Assemblies:
System.Linq.Expressions.dll, System.Core.dll, netstandard.dll

変換が失敗した場合に UnaryExpression が提供される明示的な参照変換またはボックス化変換を表す null を作成します。Creates a UnaryExpression that represents an explicit reference or boxing conversion where null is supplied if the conversion fails.

public:
 static System::Linq::Expressions::UnaryExpression ^ TypeAs(System::Linq::Expressions::Expression ^ expression, Type ^ type);
public static System.Linq.Expressions.UnaryExpression TypeAs (System.Linq.Expressions.Expression expression, Type type);
static member TypeAs : System.Linq.Expressions.Expression * Type -> System.Linq.Expressions.UnaryExpression

パラメーター

expression
Expression Expression Expression

Expression プロパティを等しく設定する Operand。An Expression to set the Operand property equal to.

type
Type Type Type

Type プロパティを等しく設定する Type。A Type to set the Type property equal to.

戻り値

UnaryExpression UnaryExpression UnaryExpression

UnaryExpression と等しい NodeType プロパティと、指定した値に設定された TypeAs プロパティおよび Operand プロパティを含む Type。A UnaryExpression that has the NodeType property equal to TypeAs and the Operand and Type properties set to the specified values.

例外

ArgumentNullException ArgumentNullException ArgumentNullException

expression または type が null です。expression or type is null.

例

次の例では、使用する方法、TypeAs(Expression, Type)を作成する方法、 UnaryExpression null 許容の整数型に null 非許容の整数型の式の参照変換を表します。The following example demonstrates how to use the TypeAs(Expression, Type) method to create a UnaryExpression that represents the reference conversion of a non-nullable integer expression to the nullable integer type. 

// Create a UnaryExpression that represents a
// conversion of an int to an int?.
System.Linq.Expressions.UnaryExpression typeAsExpression =
    System.Linq.Expressions.Expression.TypeAs(
        System.Linq.Expressions.Expression.Constant(34, typeof(int)),
        typeof(int?));

Console.WriteLine(typeAsExpression.ToString());

// This code produces the following output:
//
// (34 As Nullable`1)

' Create a UnaryExpression that represents a reference
' conversion of an Integer to an Integer? (a nullable Integer).
Dim typeAsExpression As System.Linq.Expressions.UnaryExpression = _
    System.Linq.Expressions.Expression.TypeAs( _
        System.Linq.Expressions.Expression.Constant(34, Type.GetType("System.Int32")), _
        Type.GetType("System.Nullable`1[System.Int32]"))

Console.WriteLine(typeAsExpression.ToString())

' This code produces the following output:
'
' (34 As Nullable`1)

注釈

MethodプロパティUnaryExpressionはnullします。The Method property of the resulting UnaryExpression is null. IsLiftedとIsLiftedToNullプロパティが両方ともfalseします。The IsLifted and IsLiftedToNull properties are both false.

適用対象