Message

Namespace: msg Language: Lua Type: Defold Lua File: script_msg.cpp Source: engine/script/src/script_msg.cpp

Functions for passing messages and constructing URL objects.

API

msg.post

Type: FUNCTION Post a message to a receiving URL. The most common case is to send messages to a component. If the component part of the receiver is omitted, the message is broadcast to all components in the game object. The following receiver shorthands are available:

”.” the current game object “#” the current component

There is a 2 kilobyte limit to the message parameter table size.

Parameters

• receiver (string

  url

  hash) - The receiver must be a string in URL-format, a URL object or a hashed string.

• message_id (string

  hash) - The id must be a string or a hashed string.

• message (table<any, any>

  nil) (optional) - a lua table with message parameters to send.

Examples

Send “enable” to the sprite “my_sprite” in “my_gameobject”:

msg.post("my_gameobject#my_sprite", "enable")

Send a “my_message” to an url with some additional data:

local params = {my_parameter = "my_value"}
msg.post(my_url, "my_message", params)

msg.url

Type: FUNCTION This is equivalent to msg.url(nil) or msg.url(“#”), which creates an url to the current script component.

Returns

• url (url) - a new URL

Examples

Create a new URL which will address the current script:

local my_url = msg.url()
print(my_url) --> url: [current_collection:/my_instance#my_component]

msg.url

Type: FUNCTION The format of the string must be [socket:][path][#fragment], which is similar to a HTTP URL. When addressing instances:

socket is the name of a valid world (a collection) path is the id of the instance, which can either be relative the instance of the calling script or global fragment would be the id of the desired component

In addition, the following shorthands are available:

”.” the current game object “#” the current component

Parameters

• urlstring (string) - string to create the url from

Returns

• url (url) - a new URL

Examples

local my_url = msg.url("#my_component")
print(my_url) --> url: [current_collection:/my_instance#my_component]

local my_url = msg.url("my_collection:/my_sub_collection/my_instance#my_component")
print(my_url) --> url: [my_collection:/my_sub_collection/my_instance#my_component]

local my_url = msg.url("my_socket:")
print(my_url) --> url: [my_collection:]

msg.url

Type: FUNCTION creates a new URL from separate arguments

Parameters

• socket (string

  hash) (optional) - socket of the URL

• path (string

  hash) (optional) - path of the URL

• fragment (string

  hash) (optional) - fragment of the URL

Returns

• url (url) - a new URL

Examples

local my_socket = "main" -- specify by valid name
local my_path = hash("/my_collection/my_gameobject") -- specify as string or hash
local my_fragment = "component" -- specify as string or hash
local my_url = msg.url(my_socket, my_path, my_fragment)

print(my_url) --> url: [main:/my_collection/my_gameobject#component]
print(my_url.socket) --> 786443 (internal numeric value)
print(my_url.path) --> hash: [/my_collection/my_gameobject]
print(my_url.fragment) --> hash: [component]

url

Type: CLASS A URL identifies a message endpoint in Defold. Its string form is [socket:][path][#fragment]: the socket identifies a collection, the path identifies a game object, and the fragment identifies a component. Missing parts are resolved relative to the script that creates the URL. Create URLs with msg.url. The socket, path, and fragment components are exposed as hash values and can be inspected or replaced individually. URLs are commonly passed to msg.post and to functions that address game objects or components.

Members

• socket (hash) - socket component
• path (hash) - path component
• fragment (hash) - fragment component

Examples

Create a relative URL for a component on the current game object:

local sprite_url = msg.url("#sprite")
msg.post(sprite_url, "disable")
print(sprite_url.fragment) --> hash: [sprite]

Create an absolute URL by specifying all three components:

local controller_url = msg.url("main:/player#controller")
print(controller_url) --> url: [main:/player#controller]