Expression.Convert Method
Definition
Important
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Creates a UnaryExpression that represents a type conversion operation.
Overloads
Convert(Expression, Type) |
Creates a UnaryExpression that represents a type conversion operation. |
Convert(Expression, Type, MethodInfo) |
Creates a UnaryExpression that represents a conversion operation for which the implementing method is specified. |
Convert(Expression, Type)
- Source:
- UnaryExpression.cs
- Source:
- UnaryExpression.cs
- Source:
- UnaryExpression.cs
Creates a UnaryExpression that represents a type conversion operation.
public:
static System::Linq::Expressions::UnaryExpression ^ Convert(System::Linq::Expressions::Expression ^ expression, Type ^ type);
public static System.Linq.Expressions.UnaryExpression Convert (System.Linq.Expressions.Expression expression, Type type);
static member Convert : System.Linq.Expressions.Expression * Type -> System.Linq.Expressions.UnaryExpression
Public Shared Function Convert (expression As Expression, type As Type) As UnaryExpression
Parameters
- expression
- Expression
An Expression to set the Operand property equal to.
Returns
A UnaryExpression that has the NodeType property equal to Convert and the Operand and Type properties set to the specified values.
Exceptions
expression
or type
is null
.
No conversion operator is defined between expression
.Type and type
.
Examples
The following code example shows how to create an expression that represents a type conversion operation.
// Add the following directive to your file:
// using System.Linq.Expressions;
// This expression represents a type conversion operation.
Expression convertExpr = Expression.Convert(
Expression.Constant(5.5),
typeof(Int16)
);
// Print out the expression.
Console.WriteLine(convertExpr.ToString());
// The following statement first creates an expression tree,
// then compiles it, and then executes it.
Console.WriteLine(Expression.Lambda<Func<Int16>>(convertExpr).Compile()());
// This code example produces the following output:
//
// Convert(5.5)
// 5
' Add the following directive to your file:
' Imports System.Linq.Expressions
' This expression represents a type conversion operation.
Dim convertExpr As Expression = Expression.Convert(
Expression.Constant(5.5),
GetType(Int16)
)
' Print the expression.
Console.WriteLine(convertExpr.ToString())
' The following statement first creates an expression tree,
' then compiles it, and then executes it.
Console.WriteLine(Expression.Lambda(Of Func(Of Int16))(convertExpr).Compile()())
' This code example produces the following output:
'
' Convert(5.5)
' 5
Remarks
The Method property of the resulting UnaryExpression is set to the implementing method. The IsLiftedToNull property is false
. If the node is lifted, IsLifted is true
. Otherwise, it is false
.
Implementing Method
The following rules determine the implementing method for the operation:
If either
expression
.Type ortype
is a user-defined type that defines an implicit or explicit conversion operator, the MethodInfo that represents that operator is the implementing method.Otherwise:
If both
expression
.Type andtype
represent numeric or Boolean types, or nullable or non-nullable enumeration types, the implementing method isnull
.If either
expression
.Type ortype
is a reference type and an explicit boxing, unboxing, or reference conversion exists fromexpression
.Type totype
, the implementing method isnull
.
Lifted versus Non-Lifted
If the implementing method is not null
:
If
expression
.Type is assignable to the argument type of the implementing method and the return type of the implementing method is assignable totype
, the node is not lifted.If one or both of
expression
.Type ortype
is a nullable value type and the corresponding non-nullable value types are equal to the argument type and the return type of the implementing method respectively, the node is lifted.
If the implementing method is null
:
If both
expression
.Type andtype
are non-nullable, the node is not lifted.Otherwise the node is lifted.
Applies to
Convert(Expression, Type, MethodInfo)
- Source:
- UnaryExpression.cs
- Source:
- UnaryExpression.cs
- Source:
- UnaryExpression.cs
Creates a UnaryExpression that represents a conversion operation for which the implementing method is specified.
public:
static System::Linq::Expressions::UnaryExpression ^ Convert(System::Linq::Expressions::Expression ^ expression, Type ^ type, System::Reflection::MethodInfo ^ method);
public static System.Linq.Expressions.UnaryExpression Convert (System.Linq.Expressions.Expression expression, Type type, System.Reflection.MethodInfo method);
public static System.Linq.Expressions.UnaryExpression Convert (System.Linq.Expressions.Expression expression, Type type, System.Reflection.MethodInfo? method);
static member Convert : System.Linq.Expressions.Expression * Type * System.Reflection.MethodInfo -> System.Linq.Expressions.UnaryExpression
Public Shared Function Convert (expression As Expression, type As Type, method As MethodInfo) As UnaryExpression
Parameters
- expression
- Expression
An Expression to set the Operand property equal to.
- method
- MethodInfo
A MethodInfo to set the Method property equal to.
Returns
A UnaryExpression that has the NodeType property equal to Convert and the Operand, Type, and Method properties set to the specified values.
Exceptions
expression
or type
is null
.
method
is not null
and the method it represents returns void
, is not static
(Shared
in Visual Basic), or does not take exactly one argument.
No conversion operator is defined between expression
.Type and type
.
-or-
expression
.Type is not assignable to the argument type of the method represented by method
.
-or-
The return type of the method represented by method
is not assignable to type
.
-or-
expression
.Type or type
is a nullable value type and the corresponding non-nullable value type does not equal the argument type or the return type, respectively, of the method represented by method
.
More than one method that matches the method
description was found.
Remarks
The Method property of the resulting UnaryExpression is set to the implementing method. The IsLiftedToNull property is false
. If the node is lifted, IsLifted is true
. Otherwise, it is false
.
Implementing Method
The following rules determine the implementing method for the operation:
If method is not
null
, it is the implementing method. It must represent a non-void,static
(Shared
in Visual Basic) method that takes one argument.Otherwise, if either
expression
.Type ortype
is a user-defined type that defines an implicit or explicit conversion operator, the MethodInfo that represents that operator is the implementing method.Otherwise:
If both
expression
.Type andtype
represent numeric or Boolean types, or nullable or non-nullable enumeration types, the implementing method isnull
.If either
expression
.Type ortype
is a reference type and an explicit boxing, unboxing, or reference conversion exists fromexpression
.Type totype
, the implementing method isnull
.
Lifted versus Non-Lifted
If the implementing method is not null
:
If
expression
.Type is assignable to the argument type of the implementing method and the return type of the implementing method is assignable totype
, the node is not lifted.If either or both of
expression
.Type ortype
are a nullable value type and the corresponding non-nullable value types are equal to the argument type and the return type of the implementing method respectively, the node is lifted.
If the implementing method is null
:
If both
expression
.Type andtype
are non-nullable, the node is not lifted.Otherwise the node is lifted.