Refactoring Dojo Gilded Rose Kata Steve Korzinetzki @SWKCGN February 2018

code smells

Code Duplication Deodorant Comment Speculative Generality Refused Bequest Large Class Long Parameter List Divergent Change ShotGun Surgery Feature Envy Data Clumps Switch Statements Primitive Obsession Inappropriate Intimacy Lazy Class Temporary Field Message Chains Long Method Middle Man Parallel Inheritance Hierarchy Alternative Classes with Different Interfaces Conditional Complexity Combinatorial Explosion Black Sheep

Code Duplication Deodorant Comment Speculative Generality Refused Bequest Large Class Long Parameter List Divergent Change ShotGun Surgery Feature Envy Data Clumps Switch Statements Primitive Obsession Inappropriate Intimacy Lazy Class Temporary Field Message Chains Long Method Middle Man Parallel Inheritance Hierarchy Alternative Classes with Different Interfaces Conditional Complexity Combinatorial Explosion Black Sheep

Technical Debt Ward CunningHam Signee of Agile Manifesto

Refactoring Martin Fowler Refactoring: Improving The Design of existing Code

Catalog of Refactorings Composing Methods Moving Features Between Objects Organizing Data Simplifying Conditional Expressions Making Method Calls Simpler Dealing with Generalization Big Refactorings

Catalog of Refactorings Composing Methods Moving Features Between Objects Organizing Data Simplifying Conditional Expressions Making Method Calls Simpler Dealing with Generalization Big Refactorings

Example Refactoring: Decompose Conditional if (date.before (SUMMER_START) || date.after (SUMMER_END)) { charge = quantity * _winterRate + _winterServiceCharge; } else { charge = quantity * _summerRate; }

Example Refactoring: Decompose Conditional if (date.before (SUMMER_START) || date.after (SUMMER_END)) { charge = quantity * _winterRate + _winterServiceCharge; } else { charge = quantity * _summerRate; } if (notSummer(date)) { charge = winterCharge(quantity); } else { charge = summerCharge(quantity); }

Refactoring Strategies Piecemeal Refactoring Nesting Parallel Change Evolved Target Caller Creates Graceful RetreaT etc...

Two Hats adding functions refactoring

safety net of automated tests

Approval Testing And The Golden Master

Make Baby Steps

Design Patterns as Goal For Refactoring Erich Gamma Gang of Four

Keep Solid Principles in Mind

Four Rules of Simple Design Kent Beck Author of Extreme Programming

Intermediate Steps may look worse before it‘s getting better

Any Fool can write code, that a Computer understands. good Programmers write code, that humans understand. Martin Fowler Refactoring: Improving The Design of existing Code

First Make the change easy, (Warning: this might be hard!) then make the easy change Kent Beck Author of Extreme Programming

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Resources

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