Pattern: Missing name for it in multiline lambda
Issue: -
Lambda expressions are very useful in a lot of cases and they often include very small chunks of code using only one parameter. In this cases Kotlin can supply the implicit it parameter to make code more concise. However, when you are dealing with lambdas that contain multiple statements, you might end up with a code that is hard to read if you don’t specify a readable, descriptive parameter name explicitly.
Example of incorrect code:
val digits = 1234.let {
println(it)
listOf(it)
}
val digits = 1234.let { it ->
println(it)
listOf(it)
}
val flat = listOf(listOf(1), listOf(2)).mapIndexed { index, it ->
println(it)
it + index
}Example of correct code:
val digits = 1234.let { explicitParameterName ->
println(explicitParameterName)
listOf(explicitParameterName)
}
val lambda = { item: Int, that: String ->
println(item)
item.toString() + that
}
val digits = 1234.let { listOf(it) }
val digits = 1234.let {
listOf(it)
}
val digits = 1234.let { it -> listOf(it) }
val digits = 1234.let { it ->
listOf(it)
}
val digits = 1234.let { explicit -> listOf(explicit) }
val digits = 1234.let { explicit ->
listOf(explicit)
}