Hi, I have a map<string, any>, and I was won...

# announcements

[Nir Yudovitz]

Hi,
I have a map<string, any>, and I was wondering is there a way to access the values of the map
As if they where variable names.
Same way a with will work on an object.
 
Something like:
map = mapOf("one" to 1, "two" to "2")

magicWith(map) {
one // 1
two // "2"
}
(I don’t want to create a data class to reduce boilerplates)

[LeoColman]

that kind of magic doesn't exist AFAIK

[LeoColman]

But IMO doing that would be more boilerplate than using a data class

[LeoColman]

It's a single line that makes it explicit what you're doing

[LeoColman]

Passing maps around is bad as they're not explicit. "Oh, what's the key that I needed here? Let me check"

[LeoColman]

"Was it one or ONE?"

[LeoColman]

"Was it an int or a long?"

[LeoColman]

However, with a single
data class MyData(val one: Int, val two: String) would make things explicit in whichever flow you're using

[Marc Knaup]

Closest you can get is writing a Delegate and then use it like this:

magicWith(map) {
   val one by name
   val two by name
}

Or just:

val one by map
val two by map

[Marc Knaup]

Not sure if the second case is possible tbh 😄
It is!

[LeoColman]

I think the closest you can get is something like

magicWith(map) {
   it["one"] // 1
   it["two"] // 2
}

[LeoColman]

But that's using default get

[LeoColman]

Creating a property from a name in the map is impossible

[Marc Knaup]

It works 🙂

val map = mapOf("one" to 1, "two" to "2")

val one by map  // Any?
val two by map  // Any?



operator fun <Value> Map<String, Value>.getValue(thisRef: Any?, property: KProperty<*>) =
    this[property.name]

[LeoColman]

Ah, a value works, yes

[LeoColman]

I thought that they wanted a property like using a map as if it was a data class

[Marc Knaup]

Well mine is not exactly what Nir has asked for, but close. You’re right that map keys won’t magically become variable names 🙂

[Marc Knaup]

In Kotlin/JS this may even work:

with(map.asDynamic()) {
   one
   two
}

I have no idea how Kotlin/JS handles a dynamic this.

[Marc Knaup]

lol, it’s even in the documentation 😄

https://kotlinlang.org/docs/reference/delegated-properties.html#storing-properties-in-a-map

[Nir Yudovitz]

Thanks @LeoColman and @Marc Knaup for your answers!