Code Smell 41 - Regular Expression Abusers

RegEx are a wonderful tool, we should to use them carefully and not to look smart.

Problems

• Readability

• Maintainability

• Testability

• Intention Revealing

Solutions

1. Use regular expression just for string validation.

2. If you need to manipulate objects, don't make them strings.

Sample Code

Wrong

val regex = Regex("^\\+(?:[0-9a-zA-Z][– -]?){6,14}[0-9a-zA-Z]$")

view raw smart.pl hosted with ❤ by GitHub

Right

	val prefix = "\\+"
	val digit = "[0-9]"
	val space = "[– -]"
	val phoneRegex = Regex("^$prefix(?:$digit$space?){6,14}$digit$")

view raw declarative.pl hosted with ❤ by GitHub

Detection

Regular expressions are a valid tool.
There's not much automated way of checking for possible abusers. A whitelist might be of help.

Tags

• Primitive Obsession

• Abusers

Conclusion

Regular expressions are a great tool for string validation. We must use them in a declarative way and just for strings.

Names are very important to understand pattern meanings.

If we need to manipulate objects or hierarchies, we should do it in an object way.

Unless we have a conclusive benchmark of impressive performance improvement.

Relations

Code Smell 06 - Too Clever Programmer

Maxi Contieri ・ Oct 25 '20

#codenewbie #tutorial #beginners

Code Smell 20 - Premature Optimization

Maxi Contieri ・ Nov 8 '20

#oop #developing #coding #codesmell

More info

What is in a name

Credits

Photo by John Jennings on Unsplash

---

A Perl program is correct if it gets the job done before your boss fires you.

Larry Wall