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Code Smells: Farejando o código

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João Martins
João Martins

This document discusses code smells, which are signs that may indicate deeper problems in software code. It defines code smells and provides examples, such as duplicated code, long methods, and large classes. The document categorizes different code smells as couplers, change preventers, bloaters, dispensables, and abusers. It advocates refactoring code when smells are detected, comparing code maintenance to gardening work where optimizations remove unnecessary growths.

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Code Smells: Farejando o código
Code Smells: Farejando o código João Pontes UNIC
SUMÁRIO Definição Literatura Listagem Taxonomia
“We have looked at lots of code, written for projects that span the gamut from wildly successful to nearly dead. In doing so, we have learned to look for certain structures in the code that suggest—sometimes, scream for—the possibility of refactoring.” (Martin Fowler, Kent Beck) “Are warning signs about potential problems in code. Not all smells indicate a problem, but most are worthy of a look and a decision.” (William C. Wake) DEFINIÇÃO
LITERATURA 2000 - “The Pragmatic Programmer: From Journeyman to Master” “Rather than construction, software is more like gardening—it is more organic than concrete. You plant many things in a garden according to an initial plan and conditions. Some thrive, others are destined to end up as compost. […] You constantly monitor the health of the garden, and make adjustments (to the soil, the plants, the layout) as needed.”
LITERATURA 2000 - “Refactoring: Improving the Design of Existing Code” 2003 - “Refactoring Workbook” 2005 - “Refactoring to Patterns”
LITERATURA 2006 - “A Subjective Evaluation of Software Evolvability Using Code Smells: An Empirical Study” 2018 - “Refactoring: Improving the Design of Existing Code 2nd Edition)”
Duplicated Code Long Method Large Class Long Parameter List Divergent Change Shotgun Surgery Feature Envy Data Clumps Primitive Obsession Switch Statements Parallel Inheritance Hierarchies CODE SMELLS Lazy Class Speculative Generality Temporary Field Message Chains Middle Man Inappropriate Intimacy Alternative Classes with Different Interfaces Incomplete Library Class Data Class Refused Bequest Comments
Duplicated Code Long Method Large Class Long Parameter List Divergent Change Shotgun Surgery Feature Envy Data Clumps Primitive Obsession Switch Statements Parallel Inheritance Hierarchies CODE SMELLS Lazy Class Speculative Generality Temporary Field Message Chains Middle Man Inappropriate Intimacy Alternative Classes with Different Interfaces Incomplete Library Class Data Class Refused Bequest DIVIDE ET IMPERA
Duplicated Code Long Method Large Class Long Parameter List Divergent Change Shotgun Surgery Data Clumps Primitive Obsession Switch Statements Parallel Inheritance Hierarchies CODE SMELLS Lazy Class Speculative Generality Temporary Field Alternative Classes with Different Interfaces Incomplete Library Class Data Class Refused Bequest DIVIDE ET IMPERA Feature Envy Message Chains Middle Man Inappropriate Intimacy
Duplicated Code Long Method Large Class Long Parameter List Data Clumps Primitive Obsession Switch Statements CODE SMELLS Lazy Class Speculative Generality Temporary Field Alternative Classes with Different Interfaces Incomplete Library Class Data Class Refused Bequest DIVIDE ET IMPERA Feature Envy Message Chains Middle Man Inappropriate Intimacy Divergent Change Shotgun Surgery Parallel Inheritance Hierarchies
Duplicated Code Switch Statements CODE SMELLS Lazy Class Speculative Generality Temporary Field Alternative Classes with Different Interfaces Incomplete Library Class Data Class Refused Bequest DIVIDE ET IMPERA Feature Envy Message Chains Middle Man Inappropriate Intimacy Divergent Change Shotgun Surgery Parallel Inheritance Hierarchies Long Method Large Class Long Parameter List Data Clumps Primitive Obsession
Switch Statements CODE SMELLS Temporary Field Alternative Classes with Different Interfaces Incomplete Library Class Refused Bequest DIVIDE ET IMPERA Feature Envy Message Chains Middle Man Inappropriate Intimacy Divergent Change Shotgun Surgery Parallel Inheritance Hierarchies Long Method Large Class Long Parameter List Data Clumps Primitive Obsession Duplicated Code Lazy Class Speculative Generality Data Class
CODE SMELLS Incomplete Library Class DIVIDE ET IMPERA Feature Envy Message Chains Middle Man Inappropriate Intimacy Divergent Change Shotgun Surgery Parallel Inheritance Hierarchies Long Method Large Class Long Parameter List Data Clumps Primitive Obsession Duplicated Code Lazy Class Speculative Generality Data Class Switch Statements Temporary Field Alternative Classes with Different Interfaces Refused Bequest
Couplers “Smells that represent high coupling” ● Feature Envy ● Message Chains ● Middle Main ● Inappropriate Intimacy
Change Preventers “Violate the rule which says that classes and possible changes should have a one-to-one relationship” ● Divergent Change ● Shotgun Surgery ● Parallel Inheritance Hierarchies
Bloaters “Something that has grown so large that it cannot be effectively handled” ● Data Clumps ● Primitive Obsession ● Long Method ● Large Class ● Long Parameters List
Dispensables “They all represent something unnecessary that should be removed from the source code” ● Duplicated Code ● Lazy Class ● Speculative Generality ● Data Class ● Comments
Abusers “Cases where the solution does not fully exploit the possibilities of OOP” ● Switch Statements ● Temporary Field ● Alternative Classes with Different Interfaces ● Refused Bequest
Conclusão “The gardening metaphor is much closer to the realities of software development. Perhaps a certain routine has grown too large, or is trying to accomplish too much—it needs to be split into two. Things that don't work out as planned need to be weeded or pruned.” To be continued… … Refactoring Techniques
Code Smells: Farejando o código joao.pontes@softplan.com.br jpontesmartins@gmail.com Obrigado!

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Code Smells: Farejando o código

  • 4. “We have looked at lots of code, written for projects that span the gamut from wildly successful to nearly dead. In doing so, we have learned to look for certain structures in the code that suggest—sometimes, scream for—the possibility of refactoring.” (Martin Fowler, Kent Beck) “Are warning signs about potential problems in code. Not all smells indicate a problem, but most are worthy of a look and a decision.” (William C. Wake) DEFINIÇÃO
  • 5. LITERATURA 2000 - “The Pragmatic Programmer: From Journeyman to Master” “Rather than construction, software is more like gardening—it is more organic than concrete. You plant many things in a garden according to an initial plan and conditions. Some thrive, others are destined to end up as compost. […] You constantly monitor the health of the garden, and make adjustments (to the soil, the plants, the layout) as needed.”
  • 6. LITERATURA 2000 - “Refactoring: Improving the Design of Existing Code” 2003 - “Refactoring Workbook” 2005 - “Refactoring to Patterns”
  • 7. LITERATURA 2006 - “A Subjective Evaluation of Software Evolvability Using Code Smells: An Empirical Study” 2018 - “Refactoring: Improving the Design of Existing Code 2nd Edition)”
  • 8. Duplicated Code Long Method Large Class Long Parameter List Divergent Change Shotgun Surgery Feature Envy Data Clumps Primitive Obsession Switch Statements Parallel Inheritance Hierarchies CODE SMELLS Lazy Class Speculative Generality Temporary Field Message Chains Middle Man Inappropriate Intimacy Alternative Classes with Different Interfaces Incomplete Library Class Data Class Refused Bequest Comments
  • 9. Duplicated Code Long Method Large Class Long Parameter List Divergent Change Shotgun Surgery Feature Envy Data Clumps Primitive Obsession Switch Statements Parallel Inheritance Hierarchies CODE SMELLS Lazy Class Speculative Generality Temporary Field Message Chains Middle Man Inappropriate Intimacy Alternative Classes with Different Interfaces Incomplete Library Class Data Class Refused Bequest DIVIDE ET IMPERA
  • 10. Duplicated Code Long Method Large Class Long Parameter List Divergent Change Shotgun Surgery Data Clumps Primitive Obsession Switch Statements Parallel Inheritance Hierarchies CODE SMELLS Lazy Class Speculative Generality Temporary Field Alternative Classes with Different Interfaces Incomplete Library Class Data Class Refused Bequest DIVIDE ET IMPERA Feature Envy Message Chains Middle Man Inappropriate Intimacy
  • 11. Duplicated Code Long Method Large Class Long Parameter List Data Clumps Primitive Obsession Switch Statements CODE SMELLS Lazy Class Speculative Generality Temporary Field Alternative Classes with Different Interfaces Incomplete Library Class Data Class Refused Bequest DIVIDE ET IMPERA Feature Envy Message Chains Middle Man Inappropriate Intimacy Divergent Change Shotgun Surgery Parallel Inheritance Hierarchies
  • 12. Duplicated Code Switch Statements CODE SMELLS Lazy Class Speculative Generality Temporary Field Alternative Classes with Different Interfaces Incomplete Library Class Data Class Refused Bequest DIVIDE ET IMPERA Feature Envy Message Chains Middle Man Inappropriate Intimacy Divergent Change Shotgun Surgery Parallel Inheritance Hierarchies Long Method Large Class Long Parameter List Data Clumps Primitive Obsession
  • 13. Switch Statements CODE SMELLS Temporary Field Alternative Classes with Different Interfaces Incomplete Library Class Refused Bequest DIVIDE ET IMPERA Feature Envy Message Chains Middle Man Inappropriate Intimacy Divergent Change Shotgun Surgery Parallel Inheritance Hierarchies Long Method Large Class Long Parameter List Data Clumps Primitive Obsession Duplicated Code Lazy Class Speculative Generality Data Class
  • 14. CODE SMELLS Incomplete Library Class DIVIDE ET IMPERA Feature Envy Message Chains Middle Man Inappropriate Intimacy Divergent Change Shotgun Surgery Parallel Inheritance Hierarchies Long Method Large Class Long Parameter List Data Clumps Primitive Obsession Duplicated Code Lazy Class Speculative Generality Data Class Switch Statements Temporary Field Alternative Classes with Different Interfaces Refused Bequest
  • 15. Couplers “Smells that represent high coupling” ● Feature Envy ● Message Chains ● Middle Main ● Inappropriate Intimacy
  • 16. Change Preventers “Violate the rule which says that classes and possible changes should have a one-to-one relationship” ● Divergent Change ● Shotgun Surgery ● Parallel Inheritance Hierarchies
  • 17. Bloaters “Something that has grown so large that it cannot be effectively handled” ● Data Clumps ● Primitive Obsession ● Long Method ● Large Class ● Long Parameters List
  • 18. Dispensables “They all represent something unnecessary that should be removed from the source code” ● Duplicated Code ● Lazy Class ● Speculative Generality ● Data Class ● Comments
  • 19. Abusers “Cases where the solution does not fully exploit the possibilities of OOP” ● Switch Statements ● Temporary Field ● Alternative Classes with Different Interfaces ● Refused Bequest
  • 20. Conclusão “The gardening metaphor is much closer to the realities of software development. Perhaps a certain routine has grown too large, or is trying to accomplish too much—it needs to be split into two. Things that don't work out as planned need to be weeded or pruned.” To be continued… … Refactoring Techniques