Tidy First?
A compact guide to code tidying—small, behavior-preserving changes that make code easier to understand and modify before making structural changes.
Kent Beck tackles the question every developer faces: should you clean up messy code before changing it, or just dive in? His answer is nuanced—tidy first, but only when it helps.
Core Concept
Tidyings are small, low-risk refactorings that prepare code for change. They differ from full refactoring because they're quick, reversible, and focused on the immediate task. Think of them as clearing a workspace before building.
Key Tidyings
Beck catalogs specific tidying moves:
- Guard clauses — Replace nested conditionals with early returns
- Extract helper — Pull repeated code into named functions
- Normalize symmetries — Make similar code look similar
- Dead code removal — Delete what's no longer used
- Chunk statements — Group related lines with blank lines
When to Tidy
The book's central insight: tidying has costs and benefits that compound differently.
Tidy first when:
- The change will be easier to make
- You'll touch the same code again soon
- Understanding the code takes significant effort
Skip tidying when:
- You're under time pressure for a one-off fix
- The code won't be touched again
- The tidying is bigger than the actual change
Economics of Software Design
Beck connects tidying to economic thinking. Code changes have time value—options created now may pay off later. Coupling increases the cost of change; cohesion reduces it. Tidying reduces coupling locally, making future changes cheaper.
Related
- kent-beck — Author, creator of TDD and XP