A case study in object-oriented patterns identified during manual refactoring

Software design patterns are often-repeated implementations that have been identified and cataloged. These are commonly seen as useful and good patterns to implement. Occasionally the term “anti-pattern” has been used to identify less-useful patterns that also appear regularly. The exact definition of an anti-pattern is somewhat subjective, and the term has even been applied to some recognized design patterns. This paper discusses four manual refactoring case studies where patterns were discovered and cataloged. Evidence observed in the source code is used to infer how these patterns evolved. Based on these findings, preventive development practices are suggested. Potential improvements to development tools and a new method for pattern classification are suggested as subjects for future work.