System.Design 2.0.0.0 System.Object A visual designer host, such as vsprvslong, uses the class to present custom expression editor sheets to the user, and then evaluate the selected expression for design-time rendering. When you browse the property for a control in the design-time Properties grid, the visual designer displays a dialog box to set expressions for a control property. You can select the expression type based on a list of expression prefixes. When you select an expression prefix from the list, the visual designer uses the associated and objects to set, evaluate, and convert the expression string based on the syntax for that type of expression. The visual designer sets the expression for the associated control property, and then uses the evaluated expression result to assign control property values that are rendered on the design surface. The static methods get the expression editor that is associated with a particular expression prefix or expression builder. The property for an object returns the configured expression prefix. The method evaluates an input expression string. The method returns the implementation that is used to prompt for the custom expression properties in the expressions dialog box. Typically, to support a new expression type at design time, you define a unique expression prefix and provide custom and implementations. Optionally, you can provide a custom implementation that defines properties that are used to form the expression in the expressions dialog box. The expression prefix identifies the custom expression type and associates an expression with the expression builder and expression editor. When custom expressions are parsed in a page, the expression prefix is used to create instances of the associated and classes. To associate an expression prefix with an expression builder and expression editor, apply the and attributes to the custom class and configure the expression prefix for an expression builder in the expressionBuilders element in the Web configuration file. The prefix is not required, but highly recommended.

Defines a set of properties and methods for evaluating an expression that is associated with a control property at design time and to provide an expression editor sheet to the visual design host for use in the expression editor dialog box. This class is abstract.

Constructor Because the class is abstract, you cannot create an instance of the class directly using the constructor.

Initializes a new instance of the class.

2.0.0.0 Method System.Object The visual designer host uses the method to evaluate an expression and provide the design-time value for an associated control property. The visual designer uses the method to parse the expression string at design time, and then calls the method with the parsed expression data. The visual designer uses the evaluated expression result to assign control property values that are rendered on the design surface.

Evaluates an expression string and provides the design-time value for a control property.

The object referenced by the evaluated expression string, if the expression evaluation succeeded; otherwise, null. An expression string to evaluate. The expression does not include the expression prefix. An object containing additional parsing information for evaluating . This typically is provided by the expression builder. The type of the control property to which is bound. A service provider implementation supplied by the designer host, used to obtain additional design-time services. 2.0.0.0 Property System.String To be added. The expression prefix identifies the custom expression type and associates an expression with the expression builder and expression editor. When custom expressions are parsed in a page, the expression prefix is used to create instances of the associated and classes. To associate an expression prefix with an expression builder and expression editor, apply the and attributes to the custom class and configure the expression prefix for an expression builder in the expressionBuilders element in the Web configuration file. Typically, derived classes do not override the property. The base class sets the value based on the attribute for the associated object.

Gets the expression prefix that identifies expression strings that are supported by the expression editor implementation.

2.0.0.0 Method System.Web.UI.Design.ExpressionEditor Use the static method overloads to find the object that is associated with a particular expression prefix or expression builder type. For each custom expression type, an expression prefix identifies the associated expression builder and expression editor. When custom expressions are parsed in a page, the expression prefix is used to create instances of the associated and classes. To associate an expression prefix with an expression builder and expression editor, apply the and attributes to the custom class and configure the expression prefix for an expression builder in the expressionBuilders element in the Web configuration file. To find the associated expression editor for an expression prefix, the method enumerates the available implementations for a matching prefix. The implementations can be configured in the expressionBuilders section of the Web configuration file. If an available implementation defines the expression prefix, the method returns the type that is specified in the attribute of the metadata.

Returns an implementation that is associated with the specified expression prefix.

An implementation associated with ; otherwise, null, if is not defined or is not associated with an . The expression prefix used to find the associated expression editor. A service provider implementation supplied by the designer host, used to obtain additional design-time services. 2.0.0.0 Method System.Web.UI.Design.ExpressionEditor Use the static overloads to find the object that is associated with a particular expression prefix or expression builder type. For each custom expression type, an expression prefix identifies the associated expression builder and expression editor. When custom expressions are parsed in a page, the expression prefix is used to create instances of the associated and classes. To associate an expression prefix with an expression builder and expression editor, apply the and attributes to the custom class and configure the expression prefix for an expression builder in the expressionBuilders element in the Web configuration file. The method enumerates the available implementations to locate . The implementations can be configured in the expressionBuilders section of the Web configuration file. If is found in the set of available implementations, the method returns the type that is specified in the attribute of the metadata.

Returns an implementation that is associated with the specified expression builder type.

An implementation associated with ; otherwise, null, if cannot be located or has no associated . The type of the derived expression builder class, used to locate the associated expression editor. A service provider implementation supplied by the designer host, used to obtain additional design-time services. 2.0.0.0 Method System.Web.UI.Design.ExpressionEditorSheet The method returns an implementation that defines the strings that are combined to form a custom expression. The visual designer uses an expression editor sheet to prompt for one or more strings that combine into a custom expression. The base class method returns a default expression editor sheet, which uses a single input string to form the expression. The expression editor sheet defines the property grid for the expression. Therefore, the properties that the expression editor exposes become properties that can be defined for the expression in the dialog box. Classes deriving from the class optionally can override the method to provide a custom expression editor sheet. A custom expression editor sheet can allow design-time input for multiple properties, which are combined together to form the expression string. For example, the class derives from the class and provides an implementation for evaluating and associating a resource string reference with a control property at design time. The class is associated with the expression prefix Resources and the implementation. The method returns a , which defines the individual properties that form a resource reference expression.

Returns an expression editor sheet that is associated with the current expression editor.

An that defines the custom expression properties. The expression string set for a control property, used to initialize the expression editor sheet. A service provider implementation supplied by the designer host, used to obtain additional design-time services. 2.0.0.0