Loading Patchies...

Message Passing

Messages are how objects talk to each other in Patchies. Draw a cable from one object's outlet to another's inlet, and data flows along it whenever the source sends something — a number, a string, a bang, or any custom value you like.

Message passing example

In this patch, two slider objects send their values to expr $1 + $2, which adds them and forwards the result to a p5 object for display.

Note: Objects like expr use hot and cold inlets. Only the leftmost inlet ($1) triggers output — other inlets store their value silently until the hot inlet fires.

Try It

Basic examples

✨ Open this patch to see message passing live.

Exercise 1 — Button chain

  1. Create two button objects (Enter → type button)
  2. Connect the outlet of the first to the inlet of the second
  3. Click the first button — it sends a bang, causing the second to flash

Exercise 2 — Text message

  1. Create a msg object (Enter → type m 'hello world'). Mind the single quotes.
  2. Search for the logger.js preset and connect msg → logger.js
  3. Click the message object — 'hello world' appears in the virtual console

Message Types

Most Patchies messages are plain JavaScript values:

Value Example When to use
Bang { type: 'bang' } Trigger something, no data needed
Number 42, 0.5 Sliders, knobs, sensor values
String "hello" Text, commands, labels
Object { type: 'note', pitch: 60 } Structured data with named fields

The message box has a shorthand: typing bang sends { type: 'bang' } automatically. To send the literal string "bang", wrap it in quotes.

Implicit message type

Sending & Receiving in JavaScript

In any JS-enabled object (js, p5, canvas, hydra, etc.), use send() and recv():

// Send from one object...
send({ type: "bang" });
send(42);
send("hello");

// ...receive it in another
recv((data) => {
  console.log("Got:", data);
});

Tip: Drop in the logger.js preset and connect anything to it — it prints every incoming message to the virtual console, making it easy to inspect what's flowing through a cable.

See JavaScript Runner for the full API: multiple inlets and outlets, named channels, timers, and more.

Named Channels (Wireless Messaging)

You don't always need a cable. Named channels let objects communicate across any distance in the patch — useful when cables would make the patch hard to read.

Create a send <name> object and a matching recv <name> object anywhere in the patch:

[button] → [send kick]          [recv kick] → [p5]

Any message arriving at send kick's inlet immediately appears at every recv kick's outlet — no cable required.

Visual send/recv objects and the JavaScript send()/recv() API share the same channel system and are fully interoperable. See JavaScript Runner for the JS syntax.

See Also