Represents a named parameter expression(命名的参数表达式).
命名空间:
System.Linq.Expressions
程序集: System.Core（System.Core.dll 中）
System.Object
System.Linq.Expressions.Expression
System.Linq.Expressions.ParameterExpression
public class ParameterExpression : Expression
| 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.（从 Expression 继承。） | |
| 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.(替代 Expression.NodeType。) |
| Type | Gets the static type of the expression that this Expression represents.(替代 Expression.Type。) |
Dispatches to the specific visit method for this node type. For example, MethodCallExpression calls the VisitMethodCall.(替代 Expression.Accept(ExpressionVisitor)。) | ||
 | Equals(Object) | Determines whether the specified object is equal to the current object.（从 Object 继承。） |
 | Finalize() | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.（从 Object 继承。） |
| GetHashCode() | Serves as the default hash function.（从 Object 继承。） |
| GetType() | |
| MemberwiseClone() | |
| 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.（从 Expression 继承。） |
| 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.（从 Expression 继承。） |
| 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.（从 Expression 继承。） |
| ToString() | Returns a textual representation of the Expression.（从 Expression 继承。） |
| VisitChildren(ExpressionVisitor) | Reduces the node and then calls the visitor delegate on the reduced expression. The method throws an exception if the node is not reducible.（从 Expression 继承。） |
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:
// 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
