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44 lines
No EOL
3.2 KiB
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<title>world_get — Ludic</title>
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<meta name="description" content="Read one field of a model instance by numeric id (reflection ABI).">
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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#ecs">Entities & the ECS</a> <span>›</span> <span class="here">world_get</span></div>
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<div class="item-head">
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<span class="kind-badge kind-builtin">function</span>
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<h1 id="top">world_get</h1>
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</div>
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<code class="sig">world_get(target, property, field) -> int</code>
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<div class="desc"><p><code>world_get</code> reads a single field of a model instance entirely by numeric id, returning its value as an <code>int</code>. It is the id-based counterpart to the ordinary <code>position.column</code> field access that queries give you — used when the property is not known at compile time, as in a mod or a generic tool. You supply the target instance (an <code>entity</code>), the property id (from <code>world_prop_id</code>), and the field id (from <code>world_field_id</code>); the result is the stored value. Pair it with <code>world_set</code> to write. Reading a field of an instance that lacks the property is not meaningful, so guard with <code>world_has</code> first if unsure.</p></div>
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<div class="params"><h2>Parameters</h2><div class="param" id="param-target"><code class="pname">target</code><span class="pdesc">the model instance to read from, an <code>entity</code> handle</span></div><div class="param" id="param-property"><code class="pname">property</code><span class="pdesc">the property id, from <code>world_prop_id</code></span></div><div class="param" id="param-field"><code class="pname">field</code><span class="pdesc">the field id within that property, from <code>world_field_id</code></span></div></div>
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<div class="examples"><h2>Example</h2><pre data-lang="ludic">program ReadField {
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property Position { column: int = 0, row: int = 0 }
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model Player { Position }
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handler Boot phase Start {
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spawn Hero { Position { column: 7, row: 2 } }
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}
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handler Inspect phase Update {
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let position_property = world_prop_id("Position")
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let column_field = world_field_id(position_property, "column")
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for (position) in query [Position, {Player}] {
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let value = world_get(self(), position_property, column_field)
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Screen.status(string(value))
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}
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}
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}</pre></div>
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<script>Ludic.highlightAll(); Ludic.installCards(); Ludic.flashTarget();</script>
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