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Cover image for Code Smell 63 - Feature Envy
Maxi Contieri
Maxi Contieri

Posted on • Updated on • Originally published at maximilianocontieri.com

Code Smell 63 - Feature Envy

If your method is jealous and don't trust in delegation, you should start to do it.

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

Problems

  • Coupling

  • Low Reuse

  • Low Testability

  • Bad Responsibilities Assignment

  • Bijection Fault

Solutions

  1. Move method to the appropriate class.

Sample Code

Wrong

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());
 } 
}
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Right

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 responsability 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();
  }
}
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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 and avoid abusing other objects protocol.

Relations

More info

Credits

Photo by Hisu lee on Unsplash


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



This article is part of the CodeSmell Series.

Discussion (2)

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darkwiiplayer profile image
DarkWiiPlayer

Shouldn't it be the address that does the printing?

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mcsee profile image
Maxi Contieri Author

It might be another envy, but it is clearly a chance