ludic/docs/language/structure/kw-handler.md
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docs(api): per-symbol pages, fuzzy search, deep token linking, hover cards
Rebuild the API Reference around one page per symbol and richer, verified content.

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- One HTML page per symbol (kw-*, type-*, phase-*, screen-*, fn-*, annot-*, op-*)
  instead of a single scrolling page; namespace overview pages (ns-screen …
  ns-color) and a searchable index (api.html) with client-side fuzzy search.
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Content & coverage
- Full authoritative surface documented from the compiler: every keyword, type,
  the 6 phases (Start/Input/FixedUpdate/Update/LateUpdate/Render, each its own
  page), all 22 annotations, namespace methods with parameter docs, builtins,
  the world_* reflection ABI, networking, operators — 155 symbols.
- Longer, clearer explanations; "model"/"model instance" terminology, not "entity";
  descriptive identifiers in every example (Position{column,row}, Velocity{delta_x,
  delta_y}, Health{current,maximum}, Player/Enemy) — no Pos/Seg/x/dx.
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  world_query_next(property, cursor) arg order, event fields bind by name; dropped
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Tooling
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- validate.py: compiles every ```ludic example against bin/ludicc (158 compile).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-08-29 17:53:22 +03:00

38 lines
1.6 KiB
Markdown

---
id: kw-handler
name: handler
category: structure
kind: keyword
tokens: handler
sig: handler Name phase P { … }
tip: A named block the engine runs each frame during phase P.
order: 3
---
A <code>handler</code> is a named block of behavior that the engine runs automatically during a given `phase` — 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 `@Queries` annotation (or an inline `for (…) in query […]` loop) runs its body <b>once per matching model instance</b>, with each property bound by name and `self()` giving the current instance. Handlers are registered implicitly just by being declared, and you can pause one at runtime with `disable Handler` and bring it back with `enable Handler`. Keep behavior in handlers and keep data plain in properties — that separation is the whole point.
```ludic
program Runner {
property Position { column: int = 0, row: int = 0 }
property Velocity { delta_x: int = 0, delta_y: int = 0 }
model Player { Position, Velocity }
handler Boot phase Start {
spawn Hero { Position { column: 0, row: 6 }; Velocity { delta_x: 1 } }
}
handler AdvancePositions phase Update {
for (position, velocity) in query [Position, Velocity, {Player}] {
position.column = position.column + velocity.delta_x
}
}
handler DrawWorld phase Render {
Screen.clear(Color.MidnightBlue)
for (position) in query [Position, {Player}] {
Screen.fill_rectangle(x: position.column * 16, y: position.row * 16, width: 16, height: 16, color: Color.LimeGreen)
}
Screen.show()
}
}
```