ParameterExpression Class

Definition

public ref class ParameterExpression : System::Linq::Expressions::Expression

public ref class ParameterExpression sealed : System::Linq::Expressions::Expression

public class ParameterExpression : System.Linq.Expressions.Expression

public sealed class ParameterExpression : System.Linq.Expressions.Expression

type ParameterExpression = class
 inherit Expression

Public Class ParameterExpression
Inherits Expression

Public NotInheritable Class ParameterExpression
Inherits Expression

Inheritance

Object

Expression

ParameterExpression

Examples

The following example demonstrates how to create a MethodCallExpression object that prints the value of a ParameterExpression object by using the Parameter method.

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

// Creating a parameter for the expression tree.
ParameterExpression param = Expression.Parameter(typeof(int));

// Creating an expression for the method call and specifying its parameter.
MethodCallExpression methodCall = Expression.Call(
 typeof(Console).GetMethod("WriteLine", new Type[] { typeof(int) }),
 param
);

// The following statement first creates an expression tree,
// then compiles it, and then runs it.
Expression.Lambda<Action<int>>(
 methodCall,
 new ParameterExpression[] { param }
).Compile()(10);

// This code example produces the following output:
//
// 10

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

' Creating a parameter for the expression tree.
Dim param As ParameterExpression = Expression.Parameter(GetType(Integer))

' Creating an expression for the method call and specifying its parameter.
Dim methodCall As MethodCallExpression = Expression.Call(
 GetType(Console).GetMethod("WriteLine", New Type() {GetType(Integer)}),
 param
 )

' Compiling and invoking the methodCall expression.
Expression.Lambda(Of Action(Of Integer))(
 methodCall,
 New ParameterExpression() {param}
).Compile()(10)
' This code example produces the following output:
'
' 10

Remarks

Use the Parameter factory method to create a ParameterExpression.

The value of the NodeType property of a ParameterExpression object is Parameter.