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AppSettingsExpressionEditor.EvaluateExpression Method

  • Reference

Definition

Namespace:
System.Web.UI.Design
Assembly:
System.Design.dll

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

public:
 override System::Object ^ EvaluateExpression(System::String ^ expression, System::Object ^ parseTimeData, Type ^ propertyType, IServiceProvider ^ serviceProvider);
public override object EvaluateExpression (string expression, object parseTimeData, Type propertyType, IServiceProvider serviceProvider);
override this.EvaluateExpression : string * obj * Type * IServiceProvider -> obj
Public Overrides Function EvaluateExpression (expression As String, parseTimeData As Object, propertyType As Type, serviceProvider As IServiceProvider) As Object

Parameters

expression
String

An application setting expression string to evaluate. expression does not include the AppSettings expression prefix.

parseTimeData
Object

An object containing additional parsing information for evaluating expression.

propertyType
Type

The control property type.

serviceProvider
IServiceProvider

A service provider implementation supplied by the designer host, used to obtain additional design-time services.

Returns

Object

The object referenced by expression, if the expression evaluation succeeded; otherwise, null.

Remarks

The EvaluateExpression method looks up the application setting that is specified by expression, and then returns the value of the application setting.

The visual designer uses the EvaluateExpression method to evaluate an application setting expression and provide the design-time value for an associated control property. The visual designer calls the EvaluateExpression method with the expression string, and uses the evaluated expression result to assign control property values that are rendered on the design surface.

At run time, the page parser uses the EvaluateExpression and GetCodeExpression methods of the corresponding AppSettingsExpressionBuilder implementation to evaluate an expression and provide the run-time value for an associated control property.

Applies to

See also