what you guys think about nullable parameters defaulting to

Question

what you guys think about nullable parameters defaulting to null `fun foo bar Int ` can be called like `foo ` instead of having to write `fun foo bar Int = null ` I see people comonly reading the ` ` as sort of opitional in this context and I don t see the point of calling `foo null ` though makes some sense when ```val a Int = mayReturnInt foo a ``` which is also a common scenario

umar · Answer

There are few cases you really need nullable types so being explicit achieves two goals you can see that here is default argument and it is null and code will be consistent for nullable and nonnullable types

gabrielfv · Answer

I see those cases I see that there would be consistence between types given that when they have the ` ` operator they could be `null` by default and there d be no other possibility for a default value unlike 0 for `Int` or ` ` for `String`

gabrielfv · Answer

Having types not null by default and depending on an attention raising operator like ` ` makes it very clear that a value can be null That s it s role after all

gabrielfv · Answer

It also doesn t break consistency with non null parameters since `fun foo a Int = 0 ` can accept `foo null ` with `a` actually being `null` and `foo ` with `a` being `0`

gabrielfv · Answer

The other side the scenario where `fun foo bar Int ` would not be passive of being called `foo ` and would break is not a different behavior but could be due to the fact that `bar` could not be null and therefore there is no way to infer anything

benleggiero · Answer

Too confusing Looks like ` ` means optional parameter not nullable and optional I can imagine newcomers thinking that Kotlin only allows omitted optional parameters to be null and not bothering to discover the `=` syntax

benleggiero · Answer

This would also break any APIs where the designer wanted the developer to be explicit about whether something s null

gabrielfv · Answer

I don t see what you mean in this last message < benleggiero>

gabrielfv · Answer

APIs that wanted the user to call a method like `foo null ` explicitly Is there any example

umar · Answer

Can you get with use case where you need so many `nullable`s and their default must be `null`