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 to decouple.
Relations
More info
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
This article is part of the CodeSmell Series.
Last update: 2021/06/28