ParameterExpression Class
.NET Framework 4.5
Represents a named parameter expression.
Namespace: System.Linq.Expressions
Assembly: System.Core (in System.Core.dll)
The ParameterExpression type exposes the following members.
| Name | Description | |
|---|---|---|
   | CanReduce | 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.) |
| IsByRef | Indicates that this ParameterExpression is to be treated as a ByRef parameter. |
| Name | Gets the name of the parameter or variable. |
| NodeType | Returns the node type of this Expression. (Overrides Expression.NodeType.) |
| Type | Gets the static type of the expression that this Expression represents. (Overrides Expression.Type.) |
| Name | Description | |
|---|---|---|
 | Accept | Dispatches to the specific visit method for this node type. For example, MethodCallExpression calls the VisitMethodCall. (Overrides Expression.Accept(ExpressionVisitor).) |
 | Equals(Object) | Determines whether the specified object is equal to the current object. (Inherited from Object.) |
| Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
| GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
| GetType | Gets the Type of the current instance. (Inherited from Object.) |
| MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
| Reduce | 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.) |
| ReduceAndCheck | 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.) |
| ReduceExtensions | 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.) |
| ToString | Returns a textual representation of the Expression. (Inherited from Expression.) |
| VisitChildren | 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.) |
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
Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
