Maxi Contieri

Posted on Nov 4, 2020 • Edited on Jun 23, 2021 • Originally published at maximilianocontieri.com

Code Smell 16 - Ripple Effect

#programming #tutorial #beginners

Small changes yield unexpected problems.

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

Problems

Coupling

Coupling: The one and only software design problem

Maxi Contieri ・ Feb 6 '21

#webdev #programming #oop #tutorial

Solutions

Decouple.
Cover with tests.
Refactor and isolate what is changing.
Depend on interfaces.

How to Decouple a Legacy System

Maxi Contieri ・ Mar 1 '21

#codenewbie #programming #poo #tutorial

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

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);     
   }  
}