Most of modern constraint modeling languages combine rich constraint languages with mathematical notations to tackle combinatorial optimization problems. Our purpose is to introduce new component-oriented language constructs to manipulate hierarchical problems, for instance for modeling engineering system architectures with conditional sub-problems. To this end, an object-oriented modeling language is associated with a powerful constraint language. It offers the possibility of defining conditional components to be activated at solving time, declaring polymorphic components whose concrete types have to be determined, and overriding model elements. We illustrate the benefits of this new approach in the modeling process of a difficult embodiment design problem having several architectural alternatives.