Expression.Parameter Method

Definition

Namespace:

System.Linq.Expressions

Assembly:

System.Linq.Expressions.dll

Creates a ParameterExpression node that can be used to identify a parameter or a variable in an expression tree.

Overloads

Parameter(Type, String)	Creates a ParameterExpression node that can be used to identify a parameter or a variable in an expression tree.
Parameter(Type)	Creates a ParameterExpression node that can be used to identify a parameter or a variable in an expression tree.

Parameter(Type, String)

Source:

ParameterExpression.cs

Creates a ParameterExpression node that can be used to identify a parameter or a variable in an expression tree.

public:
 static System::Linq::Expressions::ParameterExpression ^ Parameter(Type ^ type, System::String ^ name);

public static System.Linq.Expressions.ParameterExpression Parameter (Type type, string? name);

static member Parameter : Type * string -> System.Linq.Expressions.ParameterExpression

Public Shared Function Parameter (type As Type, name As String) As ParameterExpression

Parameters

type

Type

The type of the parameter or variable.

name

String

The name of the parameter or variable, used for debugging or printing purpose only.

Returns

ParameterExpression

A ParameterExpression that has the NodeType property equal to Parameter and the Type and Name properties set to the specified values.

Exceptions

ArgumentNullException

type is null.

Parameter(Type)

Source:

ParameterExpression.cs

Creates a ParameterExpression node that can be used to identify a parameter or a variable in an expression tree.

public:
 static System::Linq::Expressions::ParameterExpression ^ Parameter(Type ^ type);

public static System.Linq.Expressions.ParameterExpression Parameter (Type type);

static member Parameter : Type -> System.Linq.Expressions.ParameterExpression

Public Shared Function Parameter (type As Type) As ParameterExpression

Parameters

type

Type

The type of the parameter or variable.

Returns

ParameterExpression

A ParameterExpression node with the specified name and type.

Examples

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

// 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