Kotlin Code Smell 35 - Explicit Iteration

TL;DR: Avoid index-based iteration. Embrace higher-order collection functions.

Problem

• Violation of encapsulation

• Lack of declarativeness

Solution

• Opt for forEach() or high-order iterators.

• Concealing implementation details opens up possibilities like caching, proxies, lazy loading, and more.

Sample Code

Wrong

for(i in 0 until colors.count()) {
    print(colors[i])
}

// For Kotlin 1.9 and above, the 'until' can (and should) be
// substituted with '..<' to denote a range from 0 to 
// colors.count(), excluding the end.

Right

for(color in colors) {
    println(color)
}

// Utilizing closures and arrow functions
colors.forEach { println(it) }

Exceptions

Should the problem domain necessitate elements being mapped to natural numbers like indices, then the initial method may suffice.

Always strive to draw parallels with real-world scenarios.

Conclusion

Many developers overlook this kind of code smell, dismissing it as a minor detail.

Yet, it's the accumulation of such declarative nuances that truly elevates code quality.

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Credits

• Code Smell 53 - Explicit Iteration by Maximiliano Contieri