ParameterExpression Class


Represents a named parameter expression.

Namespace:   System.Linq.Expressions
Assembly:  System.Core (in System.Core.dll)


Public Class ParameterExpression
	Inherits Expression


Indicates that the node can be reduced to a simpler node. If this returns true, Reduce() can be called to produce the reduced form.(Inherited from Expression.)


Indicates that this ParameterExpression is to be treated as a ByRef parameter.


Gets the name of the parameter or variable.


Returns the node type of this Expression.(Overrides Expression.NodeType.)


Gets the static type of the expression that this Expression represents.(Overrides Expression.Type.)


Dispatches to the specific visit method for this node type. For example, MethodCallExpression calls the VisitMethodCall.(Overrides Expression.Accept(ExpressionVisitor).)


Determines whether the specified object is equal to the current object.(Inherited from Object.)


Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)


Serves as the default hash function. (Inherited from Object.)


Gets the Type of the current instance.(Inherited from Object.)


Creates a shallow copy of the current Object.(Inherited from Object.)


Reduces this node to a simpler expression. If CanReduce returns true, this should return a valid expression. This method can return another node which itself must be reduced.(Inherited from Expression.)


Reduces this node to a simpler expression. If CanReduce returns true, this should return a valid expression. This method can return another node which itself must be reduced.(Inherited from Expression.)


Reduces the expression to a known node type (that is not an Extension node) or just returns the expression if it is already a known type.(Inherited from Expression.)


Returns a textual representation of the Expression.(Inherited from Expression.)


Reduces the node and then calls the visitor delegate on the reduced expression. The method throws an exception if the node is not reducible.(Inherited from Expression.)

Use the Parameter factory method to create a ParameterExpression.

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

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:
' 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)}),

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

Universal Windows Platform
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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