Composing Methods Refactoring: Extract Method and Inline Method

Lecture 16 of SE602 Software Re-Engineering focuses on method composition refactoring patterns, which address the pervasive Long Method and Duplicate Code smells. The cornerstone refactoring—Extract Method—is examined across its complete mechanical protocol: identifying cohesive code fragments, turning them into standalone methods with descriptive names, managing passed parameters, and handling multiple local variable assignments via query replacements. Students study complementary refactorings: Inline Method (collapsing trivial delegators), Replace Temp with Query (eliminating temporary variables that obscure method logic), and Split Temporary Variable (ensuring variables hold a single semantic value rather than being reused for unrelated computations). Code examples illustrate how composing concise, highly focused methods dramatically improves program readability and testability. Monolithic application decomposition strategies including service-oriented architecture (SOA) and the Strangler Fig pattern are examined in depth. Scholars examine program slicing algorithms, forward and backward dependency slices, and impact assessment for proposed modifications. Automated tool support, bytecode instrumentation, and static code analyzers are evaluated to detect architectural violations across repositories. Risk management frameworks, business case evaluations, and cost estimation models such as COCOMO II are analyzed for migration projects. Legal and ethical constraints surrounding reverse engineering, clean-room design implementations, and software intellectual property rights are reviewed. By engaging with solved past papers by Moaaz and Waqar Siddhu, learners gain actionable insights into recurrent university exam questions. Interactive quiz assessments on VU SIGMA facilitate rapid knowledge verification and retention of critical software re-engineering concepts. Comprehensive coverage of standard academic benchmarks ensures learners communicate with technical precision across software engineering disciplines. Detailed analysis of code smell topologies highlights the imperative of eradicating duplicate logic, long methods, and bloated god classes. Test harness construction including characterization testing and regression suites are contrasted with traditional unit testing strategies. 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.