Yet another global access coupled with laziness.

TL;DR: Don't use static functions. They are global and utilities. Talk to objects instead.

Problems

• Coupling

• Testability

• Protocol Overloading

• Cohesion

Solutions

• Class Single Responsibility Principle is to create instance. Honor it.

• Delegate method to instance.

• Create stateless objects. Don't call them helpers.

Examples

• Static class methods

• Static attributes

Sample Code

Wrong

class DateStringHelper {
   static format(date) {
     return date.toString('yyyy-MM-dd'); ;    
  }
}


DateStringHelper.format(new Date());

Right

class DateToStringFormatter {
   constructor(date){
      this.date = date;
   }

   englishFormat() {
     return this.date.toString('yyyy-MM-dd');    
  } 
}

new DateToStringFormatter(new Date()).englishFormat()

Detection

We can enforce a policy to avoid static methods (all class methods but constructors).

Tags

• Global

• Libraries

Conclusion

Class are globals disguised. Polluting their protocol with "library methods" breaks cohesion and generates coupling. We should extract static with refactorings.

In most languages we cannot manipulate classes and use them polymorphically, so we can't mock them or plug them on tests.

Therefore, we have a global reference too difficult too decouple.

Relations

Singleton: The Root of all Evil

Maxi Contieri ・ Nov 17 '20

#oop #tutorial #codenewbie #programming

Code Smell 22 - Helpers

Maxi Contieri ・ Nov 12 '20

#oop #helpers #codenewbie #beginners

More info

• Single Responsibility Principle

How to Decouple a Legacy System

Maxi Contieri ・ Mar 1 '21

#codenewbie #programming #poo #tutorial

Credits

Photo by Alex Azabache on Unsplash

There is no programming problem that can't be solved with one more level of indirection.

John McCarthy

Software Engineering Great Quotes

Maxi Contieri ・ Dec 28 '20

#codenewbie #programming #quotes #software

This article is part of the CodeSmell Series.

How to Find the Stinky parts of your Code

Maxi Contieri ・ May 21 '21

#codenewbie #tutorial #codequality #beginners

Last update: 2021/06/28