Organizing Data Refactoring: Encapsulate Field and Replace Type Code

Lecture 18 of SE602 Software Re-Engineering examines data organization refactorings that eliminate primitive obsession and expose domain abstractions. Students study Encapsulate Field, which hides public attributes behind accessor methods to prevent unrestricted external modifications. The lecture details Replace Data Value with Object, demonstrating how primitive strings and integers (such as phone numbers or currency amounts) should be upgraded into dedicated value objects with encapsulated validation logic. The lesson tackles legacy type code flags: Replace Type Code with Subclasses (leveraging inheritance for static variations) and Replace Type Code with State/Strategy (leveraging polymorphic delegation when entity states fluctuate dynamically across execution), eliminating brittle procedural switch statements across class hierarchies. Students evaluate the trade-offs between big-bang system rewrites and progressive evolutionary refactoring in mission-critical environments. The lesson explores cognitive program comprehension models, top-down hypothesis validation, and mental mappings of complex legacy architectures. Practical code illustrations demonstrate safe code transformations, automated refactoring preconditions, and behavioral equivalence preservation. Scholars analyze Chidamber-Kemerer object-oriented metrics including WMC, CBO, and RFC to quantify the architectural impact of refactoring. Cloud migration pathways including rehosting, replatforming, and cloud-native refactoring are examined as extensions of legacy modernization. The relationship between technical debt accumulation, architectural degradation, and long-term enterprise software viability is reinforced. In this lecture, students examine formal methodologies, structural transformations, and analytical metrics of software re-engineering systems. Through detailed theoretical breakdowns, the lesson explores software evolution dynamics, legacy system preservation, and maintainability enhancement. Special emphasis is placed on reverse engineering workflows, abstract syntax tree construction, and program dependency representations. Mastering these foundational software re-engineering paradigms empowers software engineers to systematically revitalize enterprise legacy platforms. Analytical exercises and architectural traces help students prepare thoroughly for Virtual University midterm and final term examinations. The curriculum systematically aligns theoretical software evolution principles with practical source code modernization across industrial codebases. Reviewing the accompanying lecture handouts and metric tables reinforces understanding of coupling, cohesion, and architectural decay. Consistent evaluation of control flow graphs, call graph hierarchies, and database schemas ensures robust preparation for academic assessments.