Once

Learn about once statements, which let you specify content that only runs once.

Sometimes it's useful to create lines of dialogue that can only ever be displayed once.

In Yarn Spinner Scripts, you can use a once statement to denote content that can only be run one single time. When the script reaches a once statement, it checks to see if it’s run before. If it has, it skips over it! Magic.

once statements are great for making sure that the player never sees certain content more than once. For example, you might want a character to never introduce themselves to the player twice.

There are two main ways you can use a once statement, which we'll explore below.

You can wrap some lines in <<once>> and <<endonce>>:

<<once>>
  // The guard will introduce herself to the player only once. 
  Guard: Hail, traveller! Well met.
  Guard: I am Alys, the guard!
<<endonce>>

You can also use an <<else>> clause within the <<once>> statement, which will be run if the relevant <<once>> content has already been seen:

<<once>>
  Guard: Hail, traveller! Well met.
<<else>>
  Guard: Welcome back.
<<endonce>>

You can also add an if to the once to run content a single time, but only when a certain condition is true. In all other cases, it will be skipped (or the else content will be run, if there is any):

<<once if $player_is_adventurer>>
  // The guard knows the player is an adventurer, so say this line, 
  // but only ever once!
  Guard: I used to be an adventurer like you, but then I took an arrow in the knee.
<<else>>
  // Either the player is not an adventurer, or we already saw the 
  // 'arrow in the knee' line.
  Guard: Greetings.
<<endonce>>

You can add <<once>> to a line, or options:

If you add once (or once if) to a line, that line will only appear once, and will be skipped over every other time it’s encountered:

Guard: Who are you? <<once>> // Show this line only one time
Guard: Go on, get lost!

Similarly, if you add it to an option, that option will only be selectable once, and will be marked as unavailable after it’s been selected.

-> What's going on? <<once>>
	Guard: The kingdom is under seige!
-> Where can I park my horse? <<once if $has_horse>>
	Guard: Over by the tavern.
-> Lovely day today!
	Guard: Uh huh.
-> I should go.
	Guard: Please do.

once statements are really useful when you want to show long, detailed content the first time it’s encountered, but you don’t want to show it every time. This means that players don’t need to mash the ‘skip line’ button over and over when they realise that they’re starting to see a long run of lines they’ve already seen:

<<once>>
	// Show long, character-establishing lines the first time
	Guard: There's nothing new to report!
	Guard: I've been at this post for hours, and I'm so bored.
	Guard: I can't wait for the end of my watch.
<<else>>
	// Show a more condensed version all other times
	Guard: Nothing to report!
<<endonce>>

once statements keep the information about whether they’ve been run or not in a variable that’s stored in your Dialogue Runner’s Variable Storage, just like any other variable. The variable isn’t directly accessible from your Yarn scripts.