Code refactoring - bad smells in code and refactoring techniques
There is a list of refactoring techniques with examples.
- Duplicated code
Extract method or Extract class
- Long method
Extract method, Inline method, replace temp variable by query, Parameter object(DTO), Replace method by method object
- Large class
Extract class, extract subclass,
- Long parameter list
Preserve whole object, Introduce parameter object
- Divergent change发散式变化
Extract class: divide class into different sub classes, in this way, several changes in a class can be made into several sub classes.
- Shortgun surgery 霰弹修改; 和发散式变化正相反
Move method, move field: put all codes need to be modified into a class for preventing from forgetness in a lot of differenct classes.
- Feature Envy 依恋情结
symptom: a method use a lot of method in another class.
Move method, Strategy, Visitor pattern
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Data clumps 数据泥团
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Primitive obsession 基本类型偏执
Replace data value with object, replace type code with class
- Switch statements : switch 惊悚现身
Replace conditional with polymorphism
- Parallel inheritance hierarchies 平行继承体系
symptom: when you create a subclass for a class, you have to create a subclass for another class.
solution: make sure that instances of one hierarchy refer to instances of the other
- Lazy class冗赘类
symptom: a class is not doing a lot of work
solution: inline class, means moving all it’s features into another class.
- speculative generality 夸夸其谈未来性
remove parameter, collapse hierarchy, inline class
- temporary field 暂时字段
extract class, introduce nullable object
- message chains过度耦合的信息链
symptom: You see message chains when a client asks one object for another object, which the client then asks for yet another object, which the client then asks for yet another another object, and so on. solution: hide delegate
- middle man 中间人
delegate
- inappropriate intimacy 不合适的亲昵行为
extract method, extract class
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alternative classes with different interfaces
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incomplete library class
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data class
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refused requests
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comments
Extract method, Rename method
