Contents > 8 Defining Custom Design Metrics and Rules > 8.2 Definition of Sets > 8.2.1 Projection > Attribute "set" Attribute "set"

The set attribute is the set counterpart of the sum attribute for metrics. If you specify a set expression using the set attribute, the set expression is evaluated for each element in the projection, and the union over all these sets is taken.

In the following example, we assume we have defined two sets for classes:

We can then define, for a package, the set of classes that have an association or dependency link with a class in the package:
<set name="AssCls" domain="package"> 
  <projection relation="context" target="class"
              set="AssCls+DepCls" />
The sets referenced in the set expression may be either all element sets, or all value sets (see also Section "Attribute "valueset""). The resulting set will be of the same type as the constituent sets.