Do To

Use Case

You want to apply some operation to an object and then return it. Sadly, the operation returns Unit (like a setter for example).

You’ll typically find such cases when working with not functional code, a common example would be non-fluent Plain Old Java Objects from external libraries.

Simple application

Although the reducing of used linenumbers here depends on how you format your code, sometimes you may find using the doTo verb more readable. We don’t suggest over using it though.

With the doTo verb:

def makeAwesomeThing =
  doTo(new Thing) { _.setAwesome(true) }

Without the verb it would be 3 lines:

def makeAwesomeThing = {
  val t = new Thing
  t.setAwesome(true)
  t
}

Multiple application

Using this doTo style allows you to use POJOs which dont expose fluent APIs in a “almost like fluet” manner:

val modifiedPojo = doTo(new LongPojo) (
  _.trim(),
  _.setAvailable(false),
  _.setUsable(true)
)