12. Class¶

object Class¶

The Haka class allows to define custom Lua object.

class.class(name, parent=nil)¶

Parameters:	name (string) – Class name. parent (Class) – Parent class to inherit from.

Create a new class.

<Class>:new(...) → instance¶

Returns:	instance (Class instance) – New instance of the class.

Create a new instance of the class.

class.isa(instance, class)¶

Parameters:	instance (Class instance) – Class instance to test. class (Class) – Class.

Check if the given instance is a class.

class.classof(instance) → class¶

Parameters:	instance (Class instance) – Class instance to test.
Returns:	class (Class) – Class of this instance.

Get the class of a given instance.

Class.method¶

Type:	table

List of methods available on instances of this class.

Special methods:

• __init: constructor function called every time a new instance of the class is created.
• __tostring: string conversion function for the class.
• __index: meta method __index
• __newindex: meta method __newindex

Example:

local A = class("A")

function A.method:f()
    print("f()")
end

local a = A:new()

a:f() -- will print 'f()'

Class.property¶

Type:	table

List of properties on this class. A property is a table containing two functions:

class.get(self) → value¶

Getter for the property. The function is called every time the user access the property on the object.

class.set(self, newvalue)¶

Setter for the property. It is called every time the user sets a new value on the property.

Example:

local A = class("A")

function A.method:__init()
    self._prop = "my prop"
end

A.property:prop = {
    function get(self) return self._prop end,
    function set(self, value) self._prop = value end
end

local a = A:new()

a.prop -- will print "my prop"
a.prop = "foo bar"

<Class>:addproperty(get, set)¶

Parameters:	get (function) – Getter for the property. set (function) – Setter for the property.

Add a dynamic property to the class instance. This property can be accessed like any other property but only exists on this instance.