Kotlin lambdas and DSL support?

Hi, Thanks for this great library. When using with kotlin, I feel it’s a bit boilerplate can be remove by using kotlin DSL and Lambda feature. For example a GenericItem:

typealias BindFunction = ViewHolder.(position: Int) -> Unit

class GenericItem(@LayoutRes val layoutId: Int, val binder: BindFunction) : Item() {
    override fun bind(viewHolder: ViewHolder, position: Int) {
        binder(viewHolder, position)
    }

    override fun getLayout(): Int {
        return layoutId
    }
}

// when use it 
val item  = GenericItem(R.layout.item_layout){ position ->
    // the bind code 
}

By that way I can just use a GenericItem without creating a new subclass of Item.

Even more with kotlin DSL style support. We can easily build a DSL style List for RecyclerView For example :

    val adapterGroupAdapter<ViewHolder> = goupieList {
        item {
            layoutId = R.layout.item_1
            binder = {
                //bind code
            }
        }
        item {
            layoutId = R.layout.item_2
            binder = {
                //bind code
            }
        }
        item {
            layoutId = R.layout.item_3
            binder = {
                //bind code
            }
        }
    }

[lisawray]

I’m open to the idea of better Kotlin support, was thinking about it today … but I’m not convinced making Items on the fly is a major use case for Groupie. In fact, I wrote it to encourage code reuse.

Do you normally make one-off Items like this? I never have …

[Jomik]

I ended up quite liking this idea. What I have decided to do, in case groupie wants to implement similar, is to show a default item in case a setter method isn’t called. As with the header of an expandable group.

I use group to open up a basic group builder which returns a single group.

I realize that I often display lists of data, so I created a method to allow us to map over a list, with the GroupBuilder. fun <T> map(data: List<T>, init: GroupBuilder.(T) -> Unit): CompoundGroup

One of my issues has been calling methods on your parent, as with expanding a group upon touch of the header. With the below implementation it becomes simple to get the parent instance: [e-mail] I do this by having a public field which is set the moment the build method is called on the builder. override fun build() = CompoundGroup(groups).also { _instance = it }

val foo = group {
  map((0 until 10).toList()) { parentIndex ->
    expandable {
      header(R.layout.header) {
        bind { viewHolder, _ ->
          viewHolder.itemView.findViewById<TextView>(R.id.textView).text = "Parent #$parentIndex"
        }
        onClick {
          [e-mail]()
        }
      }

      content {
        map((0 until 3).toList()) {
          item(R.layout.item) {
            bind { viewHolder, _ ->
              viewHolder.itemView.findViewById<TextView>(R.id.textView).text =
                  "Child #$it of parent #$parentIndex"
            }
          }
        }
      }
    }
  }
}