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<title>@OnDespawn — Ludic</title>
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<meta name="description" content="Run a handler when a model instance is torn down, optionally knowing why.">
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<header class="nav"><div class="wrap nav-in"><a class="brand" href="index.html"><span class="logo">L</span> Ludic</a><button class="nav-toggle" aria-label="Toggle menu" aria-expanded="false">☰</button><nav class="nav-links"><a href="index.html">Home</a><a href="api.html">API Reference</a><a class="nav-cta" href="https://git.workshopsoft.io/workshopsoft/ludic">Source ↗</a></nav></div></header>
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<div class="crumbs"><a href="api.html">API Reference</a> <span>›</span> <a href="api.html#annotations">Annotations</a> <span>›</span> <span class="here">@OnDespawn</span></div>
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<div class="item-head">
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<span class="kind-badge kind-annotation">annotation</span>
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<h1 id="top">@OnDespawn</h1>
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</div>
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<code class="sig">@OnDespawn(Model, reason: r) handler Name { … }</code>
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<div class="desc"><p><code>@OnDespawn(Model)</code> is the teardown counterpart to <code>@OnSpawn</code>: it fires once for each instance of the named model as it is removed, whether by an in-world <code>despawn</code> or at program shutdown, and its body still reads the instance's outgoing field values before they are gone. With the optional <code>reason: r</code> binding it becomes reason-carrying teardown — <code>r</code> is bound to an <code>EndReason</code> the compiler passes at each teardown site (an in-world despawn passes <code>EndReason.Despawned</code>, program exit passes <code>EndReason.Quit</code>) so one hook can branch on <b>why</b> the instance is ending, the way Unreal's <code>EndPlay(reason)</code> does. Every still-live instance's hook fires at quit, which makes "no silent deaths" real: drop loot on a real death but skip it when the app is simply closing. Add <code>@Public</code> to also emit a <code>model_<Model>_despawn</code> event.</p></div>
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<div class="examples"><h2>Example</h2><pre data-lang="ludic">program DespawnHook {
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property Health { current: int = 0 }
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property Loot { gold: int = 0 }
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model Enemy { Health, Loot }
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@OnDespawn(Enemy, reason: teardown_reason) handler DropLoot {
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match teardown_reason {
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EndReason.Quit => { } # app closing — do not drop loot
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_ => { print(Loot.gold) } # died in-world — award the gold
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}
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}
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handler SpawnWave phase Start { spawn Enemy { Health { current: 10 }, Loot { gold: 25 } } }
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handler KillOne phase Render {
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for (Health) in query [Health, {Enemy}] { despawn self() } # prints 25
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quit()
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}
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}</pre></div>
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<script src="ludic-highlight.js"></script>
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<script>Ludic.highlightAll(); Ludic.installCards(); Ludic.flashTarget();</script>
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