Built-ins

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

Built-in scripting functions.

API

hash

Type: TYPEDEF Defold represents resource paths, message names, object ids, and many other identifiers as 64-bit hash values. Create one from a string with hash, or receive one from an engine API. Hashes can be compared for equality and used as table keys, but the original string is not generally recoverable in release builds.

Parameters

• value (userdata) - hashed identifier

Examples

local damage_message = hash("take_damage")

function on_message(self, message_id, message, sender)
    if message_id == damage_message then
        self.health = self.health - message.amount
    end
end

hash

Type: FUNCTION All ids in the engine are represented as hashes, so a string needs to be hashed before it can be compared with an id.

Parameters

• s (string) - string to hash

Returns

• hash (hash) - a hashed string

Examples

To compare a message_id in an on-message callback function:

function on_message(self, message_id, message, sender)
    if message_id == hash("my_message") then
        -- Act on the message here
    end
end

hash_to_hex

Type: FUNCTION Returns a hexadecimal representation of a hash value. The returned string is always padded with leading zeros.

Parameters

• h (hash) - hash value to get hex string for

Returns

• hex (string) - hex representation of the hash

Examples

local h = hash("my_hash")
local hexstr = hash_to_hex(h)
print(hexstr) --> a2bc06d97f580aab

pprint

Type: FUNCTION Pretty printing of Lua values. This function prints Lua values in a manner similar to +print()+, but will also recurse into tables and pretty print them. There is a limit to how deep the function will recurse.

Parameters

• ... (any) - values to print

Examples

Pretty printing a Lua table with a nested table:

local t2 = { 1, 2, 3, 4 }
local t = { key = "value", key2 = 1234, key3 = t2 }
pprint(t)

Resulting in the following output (note that the key order in non array Lua tables is undefined):

{
  key3 = {
    1 = 1,
    2 = 2,
    3 = 3,
    4 = 4,
  }
  key2 = 1234,
  key = value,
}

script_instance

Type: TYPEDEF An engine-created state container passed as self to script lifecycle functions and callbacks. Each script component, GUI script, and render script has its own instance. Values assigned to the instance remain available for that instance’s lifetime. Script instances cannot be created directly. Store state by assigning fields to the self value supplied by the engine.

Parameters

• value (userdata) - script instance state

Examples

Initialize state and access it from an engine callback:

function init(self)
    self.health = 100

    timer.delay(1, false, function(self, handle, time_elapsed)
        self.health = self.health - 10
        print(self.health)
    end)
end