Hello everyone. Does anyone know how to properly p...

# announcements

[rdgoite]

Hello everyone. Does anyone know how to properly protect collection type properties? What I want to do is to clone the collection into an immutable one every time get() is called. However, I just found out that defining something like,

var myCollection: MutableList<String> = mutableListOf()
    private set
    get() = field.toMutableList()

is problematic because calling this.myCollection within the class itself seem to call the getter instead. My current alternative is to make it immutable collection and replace it every time there are changes. However, that seems to be a little more work than it should be. Any ideas?

[Shawn]

the official recommendation is to have a private property that holds the mutable type and have a public property that exposes it as its read-only supertype

[Shawn]

private val _list = mutableListOf<Any>()
public val list: List<Any>
  private set
  get() = _list

[Shawn]

https://kotlinlang.org/docs/reference/properties.html?origin_team=T09229ZC6#backing-properties

[Shawn]

relevant issue: https://youtrack.jetbrains.net/issue/KT-14663

[rdgoite]

Thanks @Shawn. I forgot to mention this. My concern with this approach though is that if I were using an ORM, it’s not going to work out-of-the-box. It’s not the most inconvenient thing to add annotations to change column/field names, but, it’d still be nice if I didn’t have to.