ExpressionPrefixAttribute Class
Assembly: System.Web (in system.web.dll)
[AttributeUsageAttribute(AttributeTargets::Class, AllowMultiple=false)] public ref class ExpressionPrefixAttribute sealed : public Attribute
/** @attribute AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple=false) */ public final class ExpressionPrefixAttribute extends Attribute
AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple=false) public final class ExpressionPrefixAttribute extends Attribute
Not applicable.
The ExpressionPrefixAttribute class is used at design time with expressions that are not defined in the configuration file. Use the ExpressionPrefix property to get the name of the prefix that is associated with the ExpressionPrefixAttribute object. An expression builder looks for any statements with the following form:
<%$ [expressionPrefix]:[expressionValue] %>
Then the expression builder, based on the prefix of the expression, generates code for the property assignment. The expressionPrefix parameter refers to a configured expression builder, which is defined in the configuration file or through an ExpressionPrefixAttribute object.
The following code examples demonstrate how to use the ExpressionPrefixAttribute class. The attribute is applied to a custom expression builder that implements the ExpressionBuilder abstract class. This implementation of ExpressionBuilder returns an evaluated statement that is passed to the expression. To run this example, you must first register the custom expression builder in the Web.config file. The first code example demonstrates how to register the custom expression builder in the Web.config file.
<configuration>
<system.web>
<compilation>
<expressionBuilders>
<add expressionPrefix="MyCustomExpression"
type="MyCustomExpressionBuilder"/>
</expressionBuilders>
</compilation>
</system.web>
</configuration>
The second code example demonstrates how to reference the expression in an .aspx file.
<asp:Label ID="Label1" runat="server" Text="<%$ MyCustomExpression:Hello, world! %>" />
The third code example demonstrates how to develop a customized expression builder by deriving from ExpressionBuilder. To run this code example, you must place the class in the App_Code folder.
- AspNetHostingPermission for operating in a hosted environment. Demand value: LinkDemand; Permission value: Minimal.
Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.