Penlight

• Index

Contents

• Functions

Libraries

• pl
• pl.Set
• pl.app
• pl.array2d
• pl.class
• pl.compat
• pl.comprehension
• pl.config
• pl.data
• pl.dir
• pl.file
• pl.func
• pl.import_into
• pl.input
• pl.lapp
• pl.lexer
• pl.luabalanced
• pl.operator
• pl.path
• pl.permute
• pl.pretty
• pl.seq
• pl.sip
• pl.strict
• pl.stringio
• pl.stringx
• pl.tablex
• pl.template
• pl.test
• pl.text
• pl.types
• pl.url
• pl.utils
• pl.xml

Classes

• pl.Date
• pl.List
• pl.Map
• pl.MultiMap
• pl.OrderedMap

Manual

• Introduction
• Tables and Arrays
• Strings. Higher-level operations on strings.
• Paths and Directories
• Date and Time
• Data
• Functional Programming
• Additional Libraries
• Technical Choices

Examples

• seesubst.lua
• sipscan.lua
• symbols.lua
• test-cmp.lua
• test-data.lua
• test-listcallbacks.lua
• test-pretty.lua
• test-symbols.lua
• testapp.lua
• testclone.lua
• testconfig.lua
• testglobal.lua
• testinputfields.lua
• testinputfields2.lua
• testxml.lua
• which.lua

Module pl.class

Provides a reuseable and convenient framework for creating classes in Lua.

Two possible notations:

B = class(A)
class.B(A)

The latter form creates a named class within the current environment. Note that this implicitly brings in pl.utils as a dependency.

See the Guide for further discussion

Functions

_init (...)	initializes an instance upon creation.
instance:is_a (some_class)	checks whether an instance is derived from some class.
some_class:class_of (some_instance)	checks whether an instance is derived from some class.
some_class:cast (some_instance)	cast an object to another class.
class (base, c_arg, c)	create a new class, derived from a given base class.

Functions

_init (...)

initializes an instance upon creation.

Parameters:

• ... parameters passed to the constructor

Usage:

local Cat = class()
function Cat:_init(name)
  --self:super(name)   -- call the ancestor initializer if needed
  self.name = name
end

local pussycat = Cat("pussycat")
print(pussycat.name)  --> pussycat

instance:is_a (some_class)

checks whether an instance is derived from some class. Works the other way around as class_of. It has two ways of using; 1) call with a class to check against, 2) call without params.

Parameters:

• some_class class to check against, or nil to return the class

Returns:

true if instance is derived from some_class, or if some_class == nil then it returns the class table of the instance

Usage:

local pussycat = Lion()  -- assuming Lion derives from Cat
if pussycat:is_a(Cat) then
  -- it's true, it is a Lion, but also a Cat
end

if pussycat:is_a() == Lion then
  -- It's true
end

some_class:class_of (some_instance)

checks whether an instance is derived from some class. Works the other way around as is_a.

Parameters:

• some_instance instance to check against

Returns:

true if some_instance is derived from some_class

Usage:

local pussycat = Lion()  -- assuming Lion derives from Cat
if Cat:class_of(pussycat) then
  -- it's true
end

some_class:cast (some_instance)

cast an object to another class. It is not clever (or safe!) so use carefully.

Parameters:

• some_instance the object to be changed

class (base, c_arg, c)

create a new class, derived from a given base class. Supporting two class creation syntaxes: either Name = class(base) or class.Name(base). The first form returns the class directly and does not set its _name. The second form creates a variable Name in the current environment set to the class, and also sets _name.

Parameters:

• base optional base class
• c_arg optional parameter to class constructor
• c optional table to be used as class