Developing a DSL Graphical Notation - Eclipse Modeling Project: A Domain-Specific Language Toolkit - page 199

Element Property Value

Feature Value Spec Feature NamedElement.name : String

Body self.opposite.owner.name.toLower()

Language ocl

Feature Label Mapping Diagram Label Diagram Label LinkTarget

Editor Pattern {0}..{1}

Edit Pattern {0}..{1}

Features TypedElement.lowerBound : EInt,

TypedElement.upperBound : EInt

View Pattern {0}..{1}

Link Constraints

Target End Constraint Body *

Language ocl

* Here's the sad truth about creating a constraint to prevent aggregation
links from targeting types other than the source—or, in the case of moment inter-
vals, other than moment intervals or moment interval details. OCL gives us no
simple solution, such as oppositeEnd.oclIsTypeOf(self) . The reason is
that the argument to oclIsTypeOf() must be a type literal, leaving us with this
rather large expression:

(oppositeEnd.oclIsTypeOf(dnc::MomentInterval) and
self.oclIsTypeOf(dnc::MomentInterval))
or
(oppositeEnd.oclIsTypeOf(dnc::MomentInterval) and
self.oclIsTypeOf(dnc::MIDetail))

or
(oppositeEnd.oclIsTypeOf(dnc::Role) and self.oclIsTypeOf(dnc::Role))
or

(oppositeEnd.oclIsTypeOf(dnc::Party) and self.oclIsTypeOf(dnc::Party))
or

(oppositeEnd.oclIsTypeOf(dnc::Place) and self.oclIsTypeOf(dnc::Place))
or

(oppositeEnd.oclIsTypeOf(dnc::Thing) and self.oclIsTypeOf(dnc::Thing))
or

(oppositeEnd.oclIsTypeOf(dnc::Description) and
self.oclIsTypeOf(dnc::Description))