Last week we released v0.7.1 of our Human-Usable Textual Notation implementation. It’s available as part of Epsilon 0.8.1. In this release, we’ve aligned our implementation more closely to the OMG specification, and added some new features. Here’s a summary of the changes:
Validation
An error is now produced when enumerations, data types and abstract classes are specified as the type of an object.
An error is now produced for objects that do not specify the value of attributes with a lower bound greater than zero.
Adjectives
Positive adjectives are no longer prefixed with the # symbol. For instance:
DogPackage {
male Dog "Fido" {} // old syntax was #male Dog
}
Adjectives prefixed with the # symbol will cause a deprecation warning.
Enumeration Values
Support for enumeration values in association instances has been added. The syntax is:
DogPackage {
Dog "Lassie" {
breed: Collie // Enumeration value
name: "Lassie" // String value
}
}
Classifier-Level Attributes
Support for classifier-level attributes has been added. The syntax is:
DogPackage {
Dog.breed: Collie; // All dogs in this package are Collies by default
Dog "Lassie" {}
Dog "Jessie" {}
Dog "Scooby" {
breed: GreatDane
}
}
Classifier-level attribute values take precedence over any default value rules specified in a HUTN configuration model.
Associations: Block and Infix Notations
Support for association blocks has been added. Assuming that the Family class has a reference called “pets” accepting objects of type Dog, the syntax is:
DogPackage {
Family "The Smiths" {}
Dog "Rover" {}
pets {
Family "The Smiths"
Dog "Rover" // Refers to the existing Pet object, defined above
Family "The Smiths"
Dog "Fido" // Created automatically by the association block
}
}
Similarly, associations may be specified using an infix notation. The example above could be written:
DogPackage {
Family "The Smiths" {}
Dog "Rover" {}
Family "The Smiths" pets Dog "Rover";
Family "The Smiths" pets Dog "Fido";
}
We hope you find the improved validation and more flexible syntax useful. You can update your installation using the Eclipse update manager, or follow the instructions on the Epsilon download page.
