AppSettingsExpressionEditor::EvaluateExpression Method (String^, Object^, Type^, IServiceProvider^)

 

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

Namespace:   System.Web.UI.Design
Assembly:  System.Design (in System.Design.dll)

public:
virtual Object^ EvaluateExpression(
	String^ expression,
	Object^ parseTimeData,
	Type^ propertyType,
	IServiceProvider^ serviceProvider
) override

Parameters

expression
Type: System::String^

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

parseTimeData
Type: System::Object^

An object containing additional parsing information for evaluating expression.

propertyType
Type: System::Type^

The control property type.

serviceProvider
Type: System::IServiceProvider^

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

Return Value

Type: System::Object^

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

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.

.NET Framework
Available since 2.0
Return to top
Show: