Is it possible to something similar to be done in Kotlin <https://developer.mozilla.org/en-US/docs/W...

# announcements

[zain]

Is it possible to something similar to be done in Kotlin https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign

[gildor]

For Kotlin JS or for other targets too?

[zain]

In Kotlin JVM actually

[gildor]

Depends on what is your JSON in JVM

if instead of JSON you use Map<K, V> it’s easy, just sum 2 maps

[zain]

What if I want to mutate just a specific part of the object but we have val on the underlying data class is this even possible.

data class Family(val member: List<String>, val avgAge: Int, val origin: String)

// get from the database
val family =  Family(listOf("a", "b"), 10, "India")

val updatedFamily = family.apply { 
        origin = "UK"
}

[christophsturm]

family.copy(origin = "UK")

[christophsturm]

most object.assign usecases are very tied to how javascript objects work. so in kotlin most of the time you will use data classes and a copy constructor

[christophsturm]

or create your own dsl

[Vampire]

Why would you create a copy constructor for a data class?

[Vampire]

What is wrong with the copy function?

[zain]

Thanks that makes sense, and I exactly wanted to this feature.

[christophsturm]

I’m talking about the autogenerated copy constructor

[Vampire]

There is not auto-generated copy constructor

[Vampire]

There is only an auto-generated copy function afaik

[christophsturm]

yeah its actually a copy method

[Vampire]

copy constructor: MyDataClass(aDataClassInstance)
copy function: aDataClassInstance.copy()

[christophsturm]

hmm yeah you are right. i thought its also called a copy constructor, but i was wrong

[christophsturm]

correct naming ftw!

[Vampire]

Might seem like nit-picking, but I'm not a Kotlin expert and meant the question honest. 🙂

[zain]

Don't take things seriously have fun

[christophsturm]

no problem, it was useful to me because i know more than before now