You can access or set .NET indexed properties dynamically using the DYNAMIC-PROPERTY function by providing a character expression for the property name, along with an object reference, the THIS-OBJECT system reference, or a class type. At runtime, the AVM determines the actual type, resolves the property name expression, validates the property name against the actual type, and validates and performs the assignment.
This is the syntax of the DYNAMIC-PROPERTY function:
Element descriptions for these syntax diagrams follow:
return-value
Specifies a data element that is assigned the value returned when you execute the property's GET accessor. The appropriate CAST or ABL data type conversion function is applied to convert the property's value to the data type of return-value.
object-reference
Specifies a reference to a .NET class instance that exposes the specified property as an instance member. The compiler allows object-reference to be declared as any object type. At runtime, the object type must resolve to the type that exposes the property.
class-type-name
Specifies the name of a .NET class type that defines the specified property as a static member. This is a CHARACTER expression that the AVM evaluates to the type name of a class at runtime. It must be the name of a class: interfaces are not valid.
property-name
Specifies a CHARACTER expression that evaluates to the property's name at runtime. For non-dynamic access, you can refer to a .NET indexed property without using the property name. In dynamic access, however, you must use the property name.
index
Specifies an index of the specified element. For a .NET indexed property, index is an expression for the specified element. At compile time, index can be any data type that ABL supports for indexers. However, at runtime, it must resolve to a data type appropriate to the property type.
new-value
The value of any data type that can be assigned to the property.
Note: The value of new-value cannot be converted to the property's type.
ABL also provides the GetPropertyValue( ) and SetPropertyValue( ) methods with functionality similar to the DYNAMIC-PROPERTY function and statement, respectively. Use the GetPropertyValue( ) and SetPropertyValue( ) methods to access and set a property value at runtime, when you do not know the property's name or type at compile time. There is a difference between GetPropertyValue( ) or SetPropertyValue( ) and DYNAMIC-PROPERTY—using GetPropertyValue( ) or SetPropertyValue( )requires an instance of Progress.Lang.Class in addition to the object reference when accessing instance properties.
Conversions between the property type and the source type of a SET or the target type of a GET succeed as long as the conversion between the data type of the source and the data type of the target of the assignment is supported. The AVM does the required conversions automatically as if there were a CAST or an ABL data type conversion function such as STRING or INTEGER present.
