Objects or Functions need too many arguments to work.
TL;DR: Don't pass more than three arguments to your functions.
Problems
Low maintainability
Low Reuse
Coupling
Solutions
Find cohesive relations among arguments
Create a "context".
Consider using a Method Object Pattern.
Avoid "basic" Types: strings, arrays, integers, etc. Think on objects.
Exceptions
- Operations in real world needing not cohesive collaborators.
Sample Code
Wrong
public class Printer {
void print(String documentToPrint,
String papersize,
String orientation,
boolean grayscales,
int pagefrom,
int pageTo,
int copies,
float marginLeft,
float marginRight,
float marginTop,
float marginBotton
){
}
}
Right
final public class PaperSize {
//...
}
final public class Document {
//...
}
final public class PrintMargins {
//...
}
final public class PrintRange {
//...
}
final public class ColorConfiguration {
//...
}
final public class PrintOrientation {
//...
}
final public class PrintSetup {
public PrintSetup(PaperSize papersize,
PrintOrientation orientation,
ColorConfiguration color,
PrintRange range,
int copiesCount,
PrintMargins margins
){}
}
final public class Printer {
void print(Document documentToPrint,
PrintSetup setup
){
}
}
Detection
Most linters warn when the arguments list is too large.
Tags
- primitive
Conclusion
Relate arguments and group them.
Always favor real world mappings. Find in real world how to group the arguments in cohesive objects.
If a function gets too many arguments, some of them might be related to the class construction. This is a design smell too.
Relations
Credits
Photo by Tobias Tullius on Unsplash
This article is part of the CodeSmell Series.
Last update: 2021/06/13
Top comments (1)
I don't really follow you on this one. I understand what you want to demonstrate but your solution is using classes as data bags. Also, having too much parameters on a method does not seem to be really the problem, since your PrintSetup class does it too. To me, the big issue here is that the language itself does not support named parameters in function calls. With this it would make the code more readable and maintainable.