Classes

Classes are the template by which you create instances. Classes can also be subclassed, allowing you to extend (reuse) functionality of an existing class. This concept of extending classes and creating instances is the driving force behind OOP practices.

Discussion

Conventions

Generally a class name will be represented as a capitalized string identifier. For example "Person" is a good class identifier.

Organization

You should generally create a single Lua file for each class or subclass you wish to create, using the class indentifier as the file name. For example, a "Person" class should be stored in a file named Person.lua.

How you organize classes is left to personal preference, but a good practice is to keep your classes in a "classes" directory, and require them as needed.

For example, your file tree might look like the following:

project
  classes/
    Person.lua
  main.lua

Class Creation

A base class is created using the Classy create method. You can optionally add an constructor function if you plan on passing arguments to your class when creating instances.

See the Subclasses section for details on creating a subclass.

A Class File

A class file simply consists of the class template, which is then returned at the end of the file.

Example

classes/Person.lua

local Classy = require("plugin.classy")

--#########################################################
--# Person Class
--#########################################################
local Person = Classy.create("Person")

function Person:constructor(name)
  self.name = name
end

function Person:getName()
  return self.name
end

return Person

You can then require this class wherever you need it.

Example

main.lua

local Person = require("classes.Person")

--create instance
local person = Person:new("Marla")
--use instance
print(person:getName()) --> Marla

See the Subclasses section for information on how to set up your subclass files. See the Instances section for more information on using instances.

Class Examples

Basic Class

local Classy = require("plugin.classy")

--class
local Person = Classy.create("Person")

--#########################################################
--# Instance Examples
local p1 = Person:new()
p1.age = 26

local p2 = Person:new()
p2.age = 45

print(p1.age) --> 26
print(p2.age) --> 45

Class with Defaults

local Classy = require("plugin.classy")

--class
local Person = Classy.create("Person", { age = 23 })

--#########################################################
--# Instance Examples
local person = Person:new()
print(person.age) --> 23 (default)

Class with Constructor

local Classy = require("plugin.classy")

--class
local Person = Classy.create("Person")
function Person:constructor(age)
  self.age  = age
end

--#########################################################
--# Instance Examples
local p1 = Person:new(23)
print(p1.age) --> 23

Class with Constructor and Defaults

local Classy = require("plugin.classy")

--class
local Person = Classy.create("Person", { age = 23 })
function Person:constructor(age)
  self.age  = age
end

--#########################################################
--# Instance Examples
local p1 = Person:new()
print(p1.age) --> 23 (default)

local p2 = Person:new(45)
print(p2.age) --> 45

Class with Methods

local Classy = require("plugin.classy")

--class
local Person = Classy.create("Person")
function Person:constructor(name)
  self.name = name
end

function Person:getName()
  return self.name
end

--#########################################################
--# Instance Examples
local p1 = Person:new("Tim")
local p2 = Person:new("Jane")

print(p1:getName()) --> Tim
print(p2:getName()) --> Jame