Add State

Right now Mira will sell to anyone, even a broke traveller with zero gold. Let’s fix that.

Update mira.bub:

title: Start
---
<<declare $gold = 8>>

Mira: Hello, traveller. Potions? I've got potions.
Mira: Five gold each. Take it or leave it.
-> Buy a health potion (5 gold) <<if $gold >= 5>>
    <<set $gold = $gold - 5>>
    Mira: Pleasure doing business. You've got {$gold} gold left.
-> I can't afford that right now. <<if $gold < 5>>
    Mira: Come back when your pockets are heavier.
-> Just looking.
    Mira: ...Still just looking?
===

Reload with r. Try buying. Try changing the <<declare $gold = 8>> to <<declare $gold = 3>>, reload, and notice the buy option becomes locked.

What’s new

<<declare>> registers the variable with its type and starting value. Bubbles infers the type from the literal: 8 is a number, "hello" is text, true is a bool. It only sets the value on the first run - subsequent runs (and save/load cycles) leave the existing value alone.

<<declare $gold = 8>>   <- first run: $gold = 8
                        <- second run: $gold unchanged (already exists)

Prefer <<declare>> for anything that should persist between sessions. See Variables for the full picture.

<<set>> assigns a new value. The right side is a full expression, so arithmetic works:

<<set $gold = $gold - 5>>

Option guards. <<if $gold >= 5>> after an option text is a guard. When the guard is false, the option stays visible in the list but available: false in the event - your UI can grey it out or hide it. Bubbles won’t let the player select a locked option.

DialogueEvent::Options(opts) => {
    for opt in &opts {
        // opt.available tells you whether to render it as selectable
    }
}

{$gold} interpolation. Variables (and any expression) inside {...} get substituted into the line text before the event reaches you. By the time your game sees "You've got {$gold} gold left.", it already reads "You've got 3 gold left." No parsing on your end.

Self-check

Before moving on:

• What happens if you set $gold = 5 and buy once? What does $gold become?
• What’s the difference between a guard (<<if>> on an option) and a conditional block (<<if>> in the body)?
• Why use <<declare>> instead of just <<set>>?

(Answers: 0; guard = option is shown but locked, conditional = lines only run at all when true; <<declare>> preserves values across save/load and is a no-op on revisit.)

Where this is going

State is working. Now let’s make the scene feel like a real place - ambient sounds, a first-visit greeting that doesn’t repeat, and a command to let your engine play a sound effect.

Next: Add Polish