Code smell

A “smell” is a metaphor for bad code, proposed by Kent Beck.

Smells proposed in Refactoring: Improving the Design of Existing Code

Perhaps the list of smells begins with Mysterious name and Duplicated code because these two are the most important. In Test-Driven Development: By Example, Kent Beck defines refactoring as “revealing intention and eliminating duplication.”

• Mysterious name
• Duplicated code
• Long function
• Long parameter list
• Global data
• Mutable data
• Divergent change
• Shotgun surgery
• Feature envy
• Data clumps
• Primitive obsession
• Repeated switches
• Loops
• Lazy element
• Speculative generality
• Temporary field
• Message chains
• Middle man
• Insider trading (code smell)
• Large class
• Alternative classes with different interfaces
• Data class
• Refused bequest
• Comments

See also

• Bad smells in test: Smells commonly found in test cases.