Critical decisions among design altern seventh atives with regards to maintainability arise early in the software design cycle. Existing comparison models relayed on the structural evolution of the used design patterns are suitable to support such decisions. However, their effectiveness on predicting maintenance effort is usually verified on a limited number of case studies under heterogeneous metrics. In this article, a multi-variable simulation model for validating the decision-making reliability of the derived formal comparison models for the significant designing problem of recursive hierarchies of part-whole aggregations, proposed in our prior work, is introduced. In the absence of a strict validation, the simulation model has been thoroughly calibrated concerning its decision-making precision based on empirical distributions from time-series analysis, approximating the highly uncertain nature of actual maintenance process. The decision reliability of the formal models has been statistically validated on a sample of 1,000 instances of design attributes representing the entire design space of the problem. Despite the limited accuracy of measurements, the results show that the models demonstrate an increasing reliability in a long-term perspective, even under assumptions of high variability. Thus, the modeling theory discussed in our prior work delivers reliable models that significantly reduce decision-risk and relevant maintenance cost.

Selecting between different design options is a crucial decision for object-oriented software developers that affects code quality characteristics. Conventionally developers use their experience to make such decisions, which leads to suboptimal results regarding code quality. In this article, a formal model for providing early estimates of quality metrics of object-oriented software implementation alternatives is proposed. The model supports software developers in making fast decisions in a systematic way early during the design phase to achieve improved code characteristics. The approach employs a comparison model related to the application of the Visitor design pattern and inheritance-based implementation on structures following the Composite design pattern. The model captures maintainability as a metric of software quality and provides precise assessments of the quality of each implementation alternative. Furthermore, the model introduces the structural maintenance cost metric based on which the progressive analysis of the maintenance process is introduced. The proposed approach has been applied to several test cases for different relevant quality metrics. The results prove that the proposed model delivers accurate estimations. Thus, the proposed methodology can be used for comparing different implementation alternatives against various measures and quality factors before code development, leading to reduced effort and cost for software maintenance.