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2.9 KiB
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50 lines
No EOL
2.9 KiB
HTML
<!doctype html>
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<head>
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<meta charset="utf-8">
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<meta name="viewport" content="width=device-width, initial-scale=1">
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<title>handler — Ludic</title>
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<meta name="description" content="A named block the engine runs each frame during phase P.">
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<link rel="stylesheet" href="base.css">
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<link rel="stylesheet" href="docs.css">
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</head>
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<body>
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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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<main class="wrap item">
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<div class="crumbs"><a href="api.html">API Reference</a> <span>›</span> <a href="api.html#structure">Program structure</a> <span>›</span> <span class="here">handler</span></div>
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<div class="item-head">
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<span class="kind-badge kind-keyword">keyword</span>
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<h1 id="top">handler</h1>
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</div>
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<code class="sig">handler Name phase P { … }</code>
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<div class="desc"><p>A <code>handler</code> is a named block of behavior that the engine runs automatically during a given <code>phase</code> — the unit that turns your data into a game. A handler with no query runs <b>once per phase tick</b>; a handler with a <code>@Queries</code> annotation (or an inline <code>for (…) in query […]</code> loop) runs its body <b>once per matching model instance</b>, with each property bound by name and <code>self()</code> giving the current instance. Handlers are registered implicitly just by being declared, and you can pause one at runtime with <code>disable Handler</code> and bring it back with <code>enable Handler</code>. Keep behavior in handlers and keep data plain in properties — that separation is the whole point.</p></div>
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<div class="examples"><h2>Example</h2><pre data-lang="ludic">program Runner {
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property Position { column: int = 0, row: int = 0 }
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property Velocity { delta_x: int = 0, delta_y: int = 0 }
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model Player { Position, Velocity }
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handler Boot phase Start {
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spawn Hero { Position { column: 0, row: 6 }; Velocity { delta_x: 1 } }
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}
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handler AdvancePositions phase Update {
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for (position, velocity) in query [Position, Velocity, {Player}] {
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position.column = position.column + velocity.delta_x
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}
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}
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handler DrawWorld phase Render {
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Screen.clear(Color.MidnightBlue)
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for (position) in query [Position, {Player}] {
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Screen.fill_rectangle(x: position.column * 16, y: position.row * 16, width: 16, height: 16, color: Color.LimeGreen)
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}
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Screen.show()
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}
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}</pre></div>
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</main>
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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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