Wizards of Lua

The Art of Spell Crafting

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Types - Managing Types

The Types module can be used to check objects for their type and to create new types.

Here is an overview of the Types functions:

Functions

Below you find short descriptions about each of the functions and some examples about how to use them in your spells.

declare (className, metatable) -> nil

The ‘declare’ function creates a new class with the given name and the optionally given superclass.

Example

Declaring a “Book” class with some functions.

Types.declare("Book")

function Book.new(title)
  local o = {title=title, pages={}}
  setmetatable(o,Book)
  return o
end

function Book:addPage(text)
  table.insert(self.pages, text)
end

Please note that there is also a shortcut for “Types.declare”:

declare("Book")

Example

Declaring the “Newspaper” class as a subclass of “Book”.

declare("Newspaper", Book)

function Newspaper.new(title)
  local o = {title=title, pages={}}
  setmetatable(o,Newspaper)
  return o
end

instanceOf (classTable, object) -> boolean

The ‘instanceOf’ function returns true if the given object is an instance of the given class.

Example

Checking if the current spell’s owner is a player.

if Types.instanceOf(Player, spell.owner) then
  print("Owner is a player")
end

type (LuaObject) -> string

The ‘type’ function returns the name of the given object’s type.

Example

Printing the type of the spell’s owner.

print( Types.type(spell.owner))

Since “Types.type” is widely used there exists also a shortcut: “type”.

print( type(spell.owner))