godot-signals-groups

1# Godot Signals & Groups (4.x)
2 
3Decouple nodes with the observer pattern (signals) and act on many nodes at once
4(groups), instead of hard-coding references between scenes. Targets **Godot 4.7**.
5 
6## When to use
7 
8- Use when a node needs to tell others "something happened" (player died, item picked
9  up, wave cleared) without holding direct references to them.
10- Use when you need to address a whole category of nodes at once ("pause all enemies",
11  "save every checkpoint").
12 
13**When *not* to use:** raw signal *syntax* basics → `godot-gdscript`; scene structure
14and instancing → `godot-nodes-scenes`. For cross-scene global events, emit from an
15autoload (see `godot-nodes-scenes`).
16 
17## Core workflow
18 
191. **Decide the direction.** A child/sub-scene should *emit* a signal upward; the parent
20   *connects* to it. This keeps the child reusable and ignorant of who listens.
212. **Declare typed signals** on the emitter; `emit()` them when the event occurs.
223. **Connect with a Callable** (`sig.connect(_on_sig)`), optionally in the editor's Node
23   dock. Use `CONNECT_ONE_SHOT` for fire-once, `bind()` to pass extra context.
244. **Use groups for broadcast**: add nodes to a named group, then iterate
25   `get_tree().get_nodes_in_group(...)` or `call_group(...)`.
265. **Disconnect when needed** (e.g. before freeing a long-lived listener) and check
27   `is_connected()` to avoid duplicate connections.
28 
29## Patterns
30 
31### 1. Emit upward, connect from the parent
32 
33```gdscript
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