We learned loops back in school. But enumerators and iterators are the next generation.

TL;DR: Don't use indices while iterating. Prefer Higher level collections.

Problems

• Encapsulation

• Declarativeness

Solutions

1. Favor foreach() or high order iterators

2. You will be able to use yield(), caches, proxies, lazy loading and much more when you hide your implementation details.

Sample Code

Wrong

for (i = 0; i < colors.count(), i++) {
  print(colors[i]);
}

Right

foreach (color of colors) {
  print(color);
}

//Closures and arrow functions
colors.foreach(color => print(color));

Detection

Linters can find this smell using regex.

There might be false positives. See exceptions below.

Exceptions

If the problem domain needs the elements to be bijected to natural numbers like indices, the first solution is adequate.

Remember all time to find real world analogies.

Tags

• Declarative

Conclusion

This kind of smell do not ring the bell to many developers because they think this is a subtlety.

Clean code is full of this few declarative things that can make a difference.

Relations

More info

Credits

Photo by Elena Mozhvilo on Unsplash

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If you get tired of writing for loops, take a break and continue later.

David Walker

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Original twitter thread by Matt Moll

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This article is part of the CodeSmell Series.

Last update: 2021/06/13