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Book Exercise Lanes

This module's exercise system is book-driven plus repo-driven. Use these local chunks and your own codebase for targeted volume after you have already learned the concept from the guide.

How To Use This Page​

  1. Finish the relevant concept page first.
  2. Solve at least one exercise from memory on a codebase of your own.
  3. Only then open the matching book chunk.
  4. Keep a mistake log with tags such as private-is-not-encapsulated, SRP labelled but not split, OCP without 2nd variant, Feature Envy missed, comment that lies, or speculative abstraction.

Lane 1: SOLID identification exercises​

Use this lane when the vocabulary is present but the labeling is unreliable.

Book chunks:

Target outcomes:

  • 5 class-level SRP labels on real code with named stakeholders
  • 3 OCP-violation labels where a switch/if-chain repeats and a new variant is on the roadmap
  • 2 LSP analyses: parent contract written out, subtype checked against it
  • 2 ISP analyses: client × method matrix drawn
  • 3 DIP direction sketches: arrow pointing from policy to detail, with the fix proposed

Lane 2: Naming and function exercises​

Use this lane when your functions and names are "fine" to you but opaque to a reviewer.

Book chunks:

Target outcomes:

  • 10 renames with before/after and a sentence of justification each
  • 3 stepdown rewrites where a 40+ line function becomes a top-level plan + named sub-functions
  • 1 comment audit on a real file: classified, deleted, or rewritten as appropriate
  • 2 Extract Function drills on code where the extracted function gets a name you are happy to read out loud

Lane 3: Smell-spotting exercises​

Use this lane when your smell vocabulary needs volume.

Book chunks:

Target outcomes:

  • a smell-card deck with at least 15 smells, each with a one-line definition and one paired move
  • 8 smell-labels on a real file with direct code quotes as evidence
  • 2 change-pattern analyses (is the recent change concentrated, scattered, or mirrored?)
  • 1 parallel-hierarchy diagnosis with a composition-based fix sketched

Lane 4: Mini-refactor exercises​

Use this lane when you can name smells but hesitate to act.

Book chunks:

Target outcomes:

  • 2 Extract Function refactors on real code, fully typed and still passing tests
  • 1 Extract Class refactor where a Data Clump becomes a domain type with behavior
  • 1 Move Function refactor that fixes a named Feature Envy
  • 1 Replace Conditional with Polymorphism where the switch is repeated in at least three places
  • 1 Introduce Parameter Object refactor shrinking a signature with four-plus parameters
  • 1 "didn't refactor" case where you documented why YAGNI applied and you chose not to move

Self-Curated Problem Set​

Build a custom set with these minimums:

  • 5 cohesion/coupling labels on real classes
  • 5 SOLID-letter violations with stakeholder or mechanism evidence
  • 5 renames with pre/post comparison
  • 5 smells with refactoring moves paired
  • 3 system-level (Divergent Change / Shotgun Surgery / Parallel Hierarchy) change-pattern analyses
  • 2 written "when not to" memos

Completion Checklist​

  • Completed at least one lane in full
  • Logged at least 12 mistakes with tags and corrections
  • Wrote at least 8 full sentence-form design critiques on real code
  • Executed at least 4 real refactors on a codebase you maintain
  • Wrote at least 2 "did not refactor" justifications based on YAGNI