# Code Smell 63 - Feature Envy

> TL;DR: Don't abuse your friend objects.

# Problems

- Coupling

- Low Reuse

- Low Testability

- Bad Responsibilities Assignment

- Bijection Fault

%[https://maximilianocontieri.com/the-one-and-only-software-design-principle]

# Solutions

1.  Move the method to the appropriate class.

# Sample Code

## Wrong

[Gist Url]: # (https://gist.github.com/mcsee/62bc32206f71d61c1d0b63dcf87f8b80)
```java
class Candidate {

 void printJobAddress(Job job) {

   System.out.println("This is your position address");

   System.out.println(job.address().street());
   System.out.println(job.address().city());
   System.out.println(job.address().ZipCode());
 } 
}
```

## Right

[Gist Url]: # (https://gist.github.com/mcsee/edaade5842cdfa8ddd474c9904942e66)
```java
class Job {

 void printAddress() {

   System.out.println("This is your job position address");

   System.out.println(this.address().street());
   System.out.println(this.address().city());
   System.out.println(this.address().ZipCode());
  
  // We might even move this responsibility directly to the address!
  // Some address information is relevant to a job and not for package tracking
 } 
}

class Candidate {
  void printJobAddress(Job job) {
    job.printAddress();
  }
}
```

# Detection

Some linters can detect a sequential pattern of collaborations with another object.

# Tags

- Coupling

# Conclusion

- We should assign responsibilities according to real object [mappers](https://maximilianocontieri.com/what-is-wrong-with-software) and avoid abusing other objects' protocol.
 
# Relations

%[https://maximilianocontieri.com/code-smell-01-anemic-models]

%[https://maximilianocontieri.com/code-smell-89-math-feature-envy]

# More info

- [Refactoring Guru](https://refactoring.guru/es/smells/feature-envy)

- [C2 Wiki](https://wiki.c2.com/?FeatureEnvySmell)

- [Wikipedia](https://en.wikipedia.org/wiki/Law_of_Demeter)

# Credits

Photo by <a href="https://unsplash.com/@lee_hisu">Hisu lee</a> on <a href="/s/photos/brothers?">Unsplash</a>
  

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> We argue that design practices which take a data-driven approach fail to maximize encapsulation because they focus too quickly on the implementation of objects. We propose an alternative object-oriented design method which takes a responsibility-driven approach.

_Rebecca Wirfs-Brock_
 
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%[https://maximilianocontieri.com/software-engineering-great-quotes]

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This article is part of the CodeSmell Series.

%[https://maximilianocontieri.com/how-to-find-the-stinky-parts-of-your-code]