Creates a UnaryExpression that represents an explicit reference or boxing conversion where nullNothingnullptra null reference (Nothing in Visual Basic) is supplied if the conversion fails.
(in System.Core.dll)
Visual Basic (Declaration)
Public Shared Function TypeAs ( _
expression As Expression, _
type As Type _
) As UnaryExpression
Dim expression As Expression
Dim type As Type
Dim returnValue As UnaryExpression
returnValue = Expression.TypeAs(expression, _
type)
public static UnaryExpression TypeAs(
Expression expression,
Type type
)
public:
static UnaryExpression^ TypeAs(
Expression^ expression,
Type^ type
)
public static function TypeAs(
expression : Expression,
type : Type
) : UnaryExpression
| Exception | Condition |
|---|
| ArgumentNullException |
expression or type is nullNothingnullptra null reference (Nothing in Visual Basic). |
The Method property of the resulting UnaryExpression is nullNothingnullptra null reference (Nothing in Visual Basic). The IsLifted and IsLiftedToNull properties are both false.
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 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)
// 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)
Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
.NET Framework
Supported in: 3.5
Reference