how can i make a function with optional non nullable parameter which will use the default when i pas...

# getting-started

[poohbar]

how can i make a function with optional non nullable parameter which will use the default when i pass in null?

[spand]

non nullable parameter
pass in null

pick 1

[poohbar]

null should mean the same thing as omit, IMHO

[spand]

That ship has sailed and it doesnt.

[Egor Trutenko]

No it shouldn't, as it leads to unexpected behavior in some cases

[spand]

But if you want to pass in null what is the problem with making it nullable ?

[spand]

Cant you just do

fun foo(input: String? = null){
val inputOrDefault = input ?: "default"
}

[poohbar]

it's ugly

[poohbar]

i know have to specify two "defaults"

[poohbar]

one null and one actual default that i want

[spand]

Yes but Kotlin is not how you want it to be. Cant change that. So now you have to choose if you want it to be nice for the caller or for the implementation.

[Hamza]

why not just make it fun foo(input: String = "defaults")

[poohbar]

because then i cant pass in a nullable variable

[Sam]

take a look at decompiled code for function overloading

[Sam]

it uses a bridge method to do that work using bitmask

[Sam]

public static final void fooBar(int value, int optionalValue) {
   }

   // $FF: synthetic method
   // $FF: bridge method
   public static void fooBar$default(int var0, int var1, int var2, Object var3) {
      if ((var2 & 2) != 0) {
         var1 = 5;
      }

      fooBar(var0, var1);
   }

[Hamza]

fun foo(a: String? ) {
foo(a?: "defaults")
}

fun foo(a: String) {

}