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Cover image for Code Smell 16 - Ripple Effect

Code Smell 16 - Ripple Effect

Maxi Contieri
Learn something new every day. - I am a senior software engineer working in industry, teaching and writing on software design, SOLID principles, DDD and TDD.
Originally published at maximilianocontieri.com Updated on ・2 min read

Small changes yield unexpected problems.

TL;DR: If small changes have big impact, you need to decouple your system.

Problems

  • Coupling

Solutions

  1. Decouple.
  2. Cover with tests.
  3. Refactor and isolate what is changing.
  4. Depend on interfaces.

Examples

  • Legacy Systems

Sample Code

Wrong

class Time {
   constructor(hour, minute, seconds) {
     this.hour = hour;    
     this.minute = minute;  
     this.seconds = seconds;  
  }
    now(){
      //call operating system
    }  
}

//Adding a TimeZone will have a big Ripple Effect
//Changing now() to consider timezine will also bring the effect
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Right

class Time {
   constructor(hour, minute, seconds, timezone) {
     this.hour = hour;    
     this.minute = minute;  
     this.seconds = seconds;  
     this.timezone = timezone;  
  }  
  //Removed now() since is invalid without context
}

class RelativeClock {
   constructor(timezone){
     this.timezone = timezone;
   }
   now(timezone){
     var localSystemTime = this.localSystemTime();
     var localSystemTimezone = this.localSystemTimezone();
     //Do some math translating timezones
     //
     return new Time(..., timezone);     
   }  
}
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Detection

Tags

  • Legacy

Conclusion

There are multiple strategies to deal with Legacy and coupled systems. We should deal with this problem before it explodes under our eyes.

Relations

More info

Credits

Photo by Jack Tindall on Unsplash


Architecture is the tension between coupling and cohesion.

Neal Ford


This article is part of the CodeSmell Series.

Last update: 2021/06/24

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