Class UML 2.4.1::Extension

Description:

An extension is used to indicate that the properties of a metaclass are extended through a stereotype, and gives the ability to flexibly add (and later remove) stereotypes to classes.

Direct Superclasses: Association

Direct Subclasses:

Class Precedence List: Extension, Association, Classifier, Namespace, Type, PackageableElement, ParameterableElement, RedefinableElement, NamedElement, TemplateableElement, Relationship, Element

Properties:

isRequired : Boolean (1 1); -- source Extension
metaclass : Class (1 1); -- source Extension
ownedEnd : ExtensionEnd (1 1); -- source Extension
endType : Type (1 *); -- source Association
isDerived : Boolean (1 1); -- source Association
memberEnd : Property (2 *); -- source Association
navigableOwnedEnd : Property (0 *); -- source Association
attribute : Property (0 *); -- source Classifier
collaborationUse : CollaborationUse (0 *); -- source Classifier
feature : Feature (0 *); -- source Classifier
general : Classifier (0 *); -- source Classifier
generalization : Generalization (0 *); -- source Classifier
inheritedMember : NamedElement (0 *); -- source Classifier
isAbstract : Boolean (1 1); -- source Classifier

If true, the Classifier does not provide a complete declaration and can typically not be instantiated. An abstract classifier is intended to be used by other classifiers e.g. as the target of general metarelationships or generalization relationships.
Default value: FALSE

isFinalSpecialization : Boolean (1 1); -- source Classifier
ownedTemplateSignature : RedefinableTemplateSignature (0 1); -- source Classifier
ownedUseCase : UseCase (0 *); -- source Classifier
powertypeExtent : GeneralizationSet (0 *); -- source Classifier
redefinedClassifier : Classifier (0 *); -- source Classifier
representation : CollaborationUse (0 1); -- source Classifier
substitution : Substitution (0 *); -- source Classifier
templateParameter : ClassifierTemplateParameter (0 1); -- source Classifier
useCase : UseCase (0 *); -- source Classifier
elementImport : ElementImport (0 *); -- source Namespace
importedMember : PackageableElement (0 *); -- source Namespace
member : NamedElement (0 *); -- source Namespace
ownedMember : NamedElement (0 *); -- source Namespace
ownedRule : Constraint (0 *); -- source Namespace
packageImport : PackageImport (0 *); -- source Namespace

References the PackageImports owned by the Namespace.
{composite}
Subsets: Element.ownedElement
Opposite: PackageImport.importingNamespace

package : Package (0 1); -- source Type
visibility : VisibilityKind (1 1); -- source PackageableElement
owningTemplateParameter : TemplateParameter (0 1); -- source ParameterableElement
isLeaf : Boolean (1 1); -- source RedefinableElement
redefinedElement : RedefinableElement (0 *); -- source RedefinableElement
redefinitionContext : Classifier (0 *); -- source RedefinableElement
clientDependency : Dependency (0 *); -- source NamedElement
name : String (0 1); -- source NamedElement
nameExpression : StringExpression (0 1); -- source NamedElement
namespace : Namespace (0 1); -- source NamedElement
qualifiedName : String (0 1); -- source NamedElement
templateBinding : TemplateBinding (0 *); -- source TemplateableElement
relatedElement : Element (1 *); -- source Relationship
ownedComment : Comment (0 *); -- source Element
ownedElement : Element (0 *); -- source Element
owner : Element (0 1); -- source Element

Constraints:

Signature: non_owned_end() : Boolean;
Description: The non-owned end of an Extension is typed by a Class.
The OCL used here is not normative.
Editor's notes: metaclass, not metaclass(). Classifier, not class
Expression: metaclass->notEmpty() and metaclass.oclIsKindOf(Classifier)
Original: metaclassEnd()->notEmpty() and metaclass()->oclIsKindOf(Class)

Signature: is_binary() : Boolean;
Description: An Extension is binary, i.e., it has only two memberEnds.
Expression: memberEnd->size() = 2

Operations:

Signature: metaclassEnd() : Property;
Description: The query metaclassEnd() returns the Property that is typed by a metaclass (as opposed to a stereotype).
The OCL used here is not normative.
Editor's notes:
Expression: result = (memberEnd - OrderedSet{ownedEnd}).asOrderedSet()->first()
Original: result = memberEnd->reject(ownedEnd)

Signature: metaclass.1() : Class;
Description: The query metaclass() returns the metaclass that is being extended (as opposed to the extending stereotype).
Expression: result = metaclassEnd().type

Signature: isRequired.1() : Boolean;
Description: The query isRequired() is true if the owned end has a multiplicity with the lower bound of 1.
Expression: result = (ownedEnd->lowerBound() = 1)

---

Send questions or comments to [email protected].