To be included in a project as a property extending a UML element, an attribute must be owned by a DSL customization element and stereotyped as «derivedPropertySpecification».

Specifying derived properties

To create and specify a derived property

  1. Select the customization element for which you want to create a derived property.

    The derived property will be created for the stereotype or metaclass, defined as a customization target in the selected customization element specification.

  2. Select Create Element > Derived Property Specification from the shortcut menu. The attribute is created.

  3. Type the attribute name. Your Model Browser should look like this at this stage:

    The attribute’s name corresponds to the name of the derived property.

    Type derived property names in camel case (i.e.,realizingActivities). 

    A property name defined in camel case will be displayed in separate words with the first word capitalized. For example, realizingActivities will be changed to Realizing Activities (visible in the user interface).

  4. Edit property values specifying the derived property in the attribute's Specification window.

    All properties are specified in the general specification pane. Some are also specified in the Tags specification pane. For detailed information, see the properties description table.

If you do not see the newly created derived property in the element’s Specification window, please read the following:

  • In the element’s Specification window, the specified derived property is visible by default only in the All properties mode. First, try switching to this mode. Also try changing the mode in which you want the derived property to be visible (click the Customize button).
  • If you have specified the derived property for the element (with the Used UML Properties property of DSL customization specified) you must add the newly created derived property to the element’s visible properties list. For detailed information, please refer to Derived properties visibility.

If you need to further customize a customization’s derived property without modifying the existing customization itself, you can create a new customization that can inherit the former one’s properties via a generalization. Then you can redefine the inherited derived property to customize it. The redefining derived property of the new customization overrides that of the original customization.

Derived property specification

The Specification window of the derived property

The following table describes the properties specified for the derived property.

PropertyDescription
Name

The name of the property.
This name will be added and visible in the specification of the element whose type is defined as a customization target.

Type

The type of the derived property values. You may set a model element type or a data type (e.g., string, boolean, orintegerfrom the UML Standard Profile) as a property value.

To display classes and components as property values, select the classifier as a type for the derived property value.

Multiplicity

The multiplicity of the derived property values.

If the multiplicity is “0..1”, the derived property value will be shown as single.
If the multiplicity is “0..*”, the derived property values will be shown as collection.

Is Read Only

If true, the derived property is read-only. You cannot edit the result elements for the derived property value.
If false, the property is read-write. You can edit the result elements for the derived property according to the expressions defined.

Is Ordered

If true, the property values are always displayed in the same order.
If false, the property values are displayed in nonpredictable order.

Is Unique

If true, the property values are unique. The same element is displayed only once.
If false, the property values may be displayed more than once.

Expression

One or more expressions of the derived property.
An expression defines the criterion for selecting result elements.

There are ten possible expression types:

  • Metachain navigation (indirect relations through chains of properties)

  • Find

  • Union

  • Exclude

  • Filter

  • Various scripts

  • Implied Relation
  • Type Test
  • Property Test
  • Operation from Model

The criterion for selecting the result elements can also be any combination of the expression types above.
For the detailed information, see Defining expressions.

Only one Simple Navigation operation criterion can be assigned to the expression of the derived property.   

Documentation

The text displayed as the derived property description in the element’s Specification window and Properties panel.

customizationTarget

The specified derived property will be added to one or more element types (stereotypes and/ or metaclasses).

The expression calculations begin from the element type of the customization target.


Related pages: