Hey guys, Can we optimise or idiotmatic way this code ? ```internal fun combineFullName(customerAddr...

# codereview

[KotlinLeaner]

Hey guys, Can we optimise or idiotmatic way this code ?

internal fun combineFullName(customerAddress: CustomerAddress?): CustomerAddress? {
    val fullName = if (customerAddress?.fullName.isNullOrEmpty()) {
        customerAddress?.firstName + " " + customerAddress?.lastName
    } else {
        customerAddress?.fullName
    }
    return customerAddress?.copy(fullName = fullName)
}

Thanks

[Joffrey]

What is fullName in the CustomerAddress definition? Can it have a value that is not first+last? Or does it always start empty/null and is then set by this function?

[KotlinLeaner]

fullName is a type of String. It has 2 condition.
1st Scenario
fullName will be null then we need to set first+last.
2nd Scenario
fullName will not be null then we don't need to set first+last because it has same value in first and last.
Thanks

[ephemient]

first+last is a bad idea. https://www.kalzumeus.com/2010/06/17/falsehoods-programmers-believe-about-names/

[Roukanken]

well, first point would be not passing nullable CustomerAddress to the function, as it serves no purpose here. Instead you would be better of using it as a receiver
and turn any callsite of combineFullName(someExpression) to someExpression?.combineFullName() getting exact same results

After that it looks pretty good, with small change:

internal fun CustomerAddress.combineFullName(): CustomerAddress {
    val fullName = if (fullName.isNullOrEmpty()) { 
        "$firstName $lastName"
    } else {
        fullName
    }
    return copy(fullName = fullName)
}

And yes, it's a bad idea 😛

[ephemient]

and it would probably make more sense as part of the construction of the class itself

[Roukanken]

Hmm true

[Joffrey]

Yeah it could just be a default value of fullName

[KotlinLeaner]

@ephemient actually I just write in short form first + last but in actual is firstName + lastname in my data class. Thanks for sharing that article. I'll remember in future

[KotlinLeaner]

How can I do in the construction of class?

[Roukanken]

data class Address(
    val first: String,
    val last: String,
    val full: String = "$first $last"
)

println(Address(first = "first", last = "last"))
println(Address(first = "first", last = "last", full = "weird full name"))

Prints

Address(first=first, last=last, full=first last)
Address(first=first, last=last, full=weird full name)

[KotlinLeaner]

Actually firstName, lastName and fullName is coming from server and it can null/empty that's why I used nullable

[Roukanken]

I chewed you out for using nullable argument for single argument function that does nothing and just returns null if it gets null - this is the purpose of ?. operator, you don't really need to handle it in function

Not for individual fields 😛 (and your above code currently does not really handle nullability... for example it would set fullName to "null null" if it got every field null, but you constructed a class from that)

[Klitos Kyriacou]

In fact, I recently received a letter through the post, addressed as "Dear null". So this happens in production code too.

[KotlinLeaner]

I got it thanks a million