kotter/com.varabyte.kotter.foundation.render/aside

aside

fun RunScope.aside(render: AsideRenderScope.() -> Unit)

A one-off render block that can be triggered within a RenderScope.run block.

Occasionally, it is useful to generate a bit of extra text that doesn't really belong in the main rendering area. An aside call looks like:

section {
  textLine("Main render text")
}.run {
  aside { textLine("Aside text") }
}

For example, you could use an aside block in a text adventure game, where there was a main area describing the current room with asides used to output the result of user actions:

val gameEngine = ...
section {
  textLine(gameEngine.roomDescription())
  textLine("Your move?")
  for (choice in gameEngine.choices()) {
    text("* "); textLine(choice)
  }
  input()
}.runUntilSignal {
  onInputEntered {
    val result = gameEngine.handle(input); clearInput()
    aside { textLine(result) }
    if (gameEngine.shouldQuit) {
      signal()
    } else {
      rerender() // The game engine state changed, update the section!
    }
  }
}

which might generate output like:

You moved north.            <-- From aside
You picked up a torch.      <-- From aside
You moved east.             <-- From aside

▼ The active rendering area begins here ▼
You are in a big room with three doors, one to the west,
one to the east, and one to the north. There is a coin
on the floor.

Your move?
* go east
* go west
* go north
* pick up coin
pick up co█

The aside block essentially prepends text in front of the active, constantly repainting block. It gives the user the illusion that there's a main rendering area that spits out historical, static text in its wake as a side effect of it running.

A compiler program could be another good example of this -- you might have a spinner plus some text saying which file is currently being compiled, with finished files output using asides.