Interface IExpression

Defines a contract for expression objects that can provide dynamic property values and participate in the RadProperty value resolution system.

Namespace: Telerik.WinControls
Assembly: Telerik.WinControls.dll

Syntax

public interface IExpression
Remarks

IExpression enables advanced property value scenarios such as data binding, calculated values, and property value forwarding. Expression objects can provide values that change over time and notify the property system when updates are needed.

Implementations participate in the property value precedence chain and can override local values, inherited values, or default values depending on their configuration and attachment to specific RadObject instances.

Methods

GetValue(RadObject, RadProperty)

Gets the current value for the specified property on the given RadObject.

Declaration
object GetValue(RadObject forObject, RadProperty property)
Parameters
RadObject forObject

The RadObject instance for which to retrieve the property value.
RadProperty property

The RadProperty whose value should be retrieved.
Returns
System.Object

The current value of the property, or UnsetValue if no value is available.
Remarks

This method is called by the property system when resolving property values. Implementations should return the appropriate value based on their expression logic or UnsetValue to allow fallback to the next value source.

OnAttach(RadObject, RadProperty)

Called when this expression is being attached to the specified property on the given RadObject.

Declaration
void OnAttach(RadObject radObject, RadProperty dp)
Parameters
RadObject radObject

The RadObject to which the expression is being attached.
RadProperty dp

The RadProperty to which the expression is being attached.
Remarks

This method provides an opportunity for expressions to initialize resources, subscribe to events, or perform other setup operations when they begin providing values for a property.

OnDetach(RadObject, RadProperty)

Called when this expression is being removed from the specified property on the given RadObject.

Declaration
void OnDetach(RadObject radObject, RadProperty dp)
Parameters
RadObject radObject

The RadObject from which the expression is being detached.
RadProperty dp

The RadProperty from which the expression is being detached.
Remarks

This method provides an opportunity for expressions to clean up resources, unsubscribe from events, or perform other cleanup operations when they are no longer providing values for a property.

SetValue(RadObject, RadProperty, Object)

Attempts to set a value through this expression.

Declaration
bool SetValue(RadObject radObject, RadProperty dp, object value)
Parameters
RadObject radObject

The RadObject on which to set the property value.
RadProperty dp

The RadProperty to set.
System.Object value

The value to set.
Returns
System.Boolean

true if the expression handled the set operation; otherwise, false.
Remarks

Most expression types are read-only and will return false from this method. Data binding expressions may support two-way binding and return true when they successfully update the underlying data source.

Extension Methods