usageHints.adoc

Hints on using DclareForMPS

General

• We have to switch on the engine at File › Settings › Other Settings › Dclare › Engine on.

• Attribute inheritance works, i.e. attributes for concept SuperConcept can be referred to in concept SubConcept extends SuperConcept.

• We can have circular change rules, as long as they don’t conflict.

  Example: In model A, we have a named node of concept X. A rule creates model B and within it a named node of concept Y. We can propagate name changes from X to Y and from Y to X.

Model change / write access

• Inside Dclare, we can only write to the model with the := operator or by calling concat() on a collection.

Syntax

• We can use variables in the Rules section by nesting them into curly braces:

  {
    node<Something> = this.someRefOfTypeSomething;
  }

• We can find opposites of references with the ~ operator:

  nlist<Inhabitant> inhabitants := this.address.~Inhabitant::home;

• We can set an attribute to optional, if it might be null. Prefix the attribute with optional, or use the intention menu.

UI

• The Context Menu › Refactoring › Extract Attribute works as expected.