Updated: October 2008
Represents a named parameter expression.
Public NotInheritable Class ParameterExpression _ Inherits Expression
Dim instance As ParameterExpression
public sealed class ParameterExpression : Expression
public ref class ParameterExpression sealed : public Expression
public final class ParameterExpression extends Expression
Use the Parameter factory method to create a ParameterExpression.
The value of the NodeType property of a ParameterExpression object is Parameter.
For example, assume that you have the following query:
companies.Where(Function(company) company.ToLower() = "coho winery" _ OrElse company.Length > 16).OrderBy(Function(company) company)
companies.Where(company => (company.ToLower() == "coho winery" || company.Length > 16)).OrderBy(company => company)
In this case, company becomes a parameter expression. To construct an expression tree for this parameter, you can use the following code:
Dim pe As ParameterExpression = Expression.Parameter(GetType(String), "company")
ParameterExpression pe = Expression.Parameter(typeof(string), "company");
You can find a complete example of using parameter expressions in expression trees in How to: Use Expression Trees to Build Dynamic Queries.
Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003
Date
History
Reason
October 2008
Added example.
Customer feedback.