Hey guys! I am at the very beginning of using Kotlin and understanding certain mechanics, if I have...

# getting-started

[Daniel Branco]

Hey guys!

I am at the very beginning of using Kotlin and understanding certain mechanics, if I have the following:

data class Foo(
   var id: Int?, 
   var name: String = "bar", 
   var anotherVar
)

I thought I could have calls like Foo() or Foo(id=1) without needing to pass all the parameters to the constructor, am I wrong? Where can I read more about constructors in Kotlin?

[ephemient]

the same applies to all callables (functions), not just constructors: all parameters must either be specified or have a default value (or both, in which case the specified value is used rather than the default)

[ephemient]

since there's no default on id or anotherVar, both must be specified

[ephemient]

also, because name is optional and precedes a required argument, anotherVar must be given by name if name is omitted

[ephemient]

https://kotlinlang.org/docs/functions.html#default-arguments

[Daniel Branco]

Thanks @ephemient

[Stephan Schroeder]

Also anotherVar needs a type. Candiates:
• Any or Any? (like Any but nullable) if you want to put anything in it.
• Or you make Foo generic:

data class Foo<T> {
   var id: Int?, 
   var name: String = "bar", 
   var anotherVar: T
)

but since you're new to Kotlin maybe generics are too advanced??