Measuring the complexity of domain-specific languages developed using MDD

The standard ISO/IEC 25010 (SQuaRE) defines appropriateness as one of the three components of functional suitability, the other two components being completeness and correctness. As users of domain-specific language (DSL) are quite often domain experts with limited programming skills, a DSL might be considered appropriate if the resulting domain-specific programs do not contain an excessive amount of nondomain-related programming elements. This paper describes a metric for measuring the appropriateness of DSLs that are developed using model-driven development (MDD), its evaluation and use. The metric measures the depth of the deepest domain-specific command within abstract syntax trees generated by a DSL. It is aimed at being used during the development of a new DSL and for comparing different DSLs defined over the same domain. It is assumed that during MDD, the metamodel describes the domain-independent part of the DSL, while the model supplies the domain-specific part. This resembles the implementation of DSLs using existing metaprogramming tools that provide off-the-shelf implementations of programming constructs but require manual implementation of the domain-specific language elements.