In Lua, we can use variables to hold both data and code, and we can use tables to hold groups of values (numbers and strings) and code assiciated with those variables too. A new example - [here] on our web site - shows how I can define such a table:

  south = {cars=3,seats=78,time="06:38",destiny="Southampton"}

add a function (code) to it:

  function capacity(of)
    local peeps = math.floor(of.cars * of.seats * 1.4)
    return peeps
  end

  south.getCapacity = capacity

I can then run that code on the data using
  takes = south.getCapacity(south)
or
  takes = south:getCapacity()

The real gains start to come when I produce a whole table of servives, perhaps of different types (trains and buses) with differing code to work out the capacity. The need for "if" and "else" type coding in the getCapacity loop melts away:

  for _,service in ipairs(services) do
    print("Can carry " .. service:getCapacity() .. " to " .. service.destiny)
  end

From our Learning to program in Lua course, running this week, again next week, and available every 2 months next year. Check [here] for the next dates.
(written 2015-11-05)

 U107 - Object Orientation - the Lua way
  [1692] Towards Object Oriented Programming in Lua - (2008-06-30)
  [1699] If you are learning Lua, here are some more examples - (2008-07-06)
  [1743] First class functions in Lua lead to powerful OO facilities - (2008-08-07)
  [1819] Calling base class constructors - (2008-10-03)
  [2318] For Lua Programmers AND for Town Planners - (2009-08-02)
  [2359] A fresh example - objects the Lua way - (2009-08-13)
  [2455] Lua examples - coroutines, error handling, objects, etc - (2009-10-15)
  [2701] Is Lua an Object Oriented language? - (2010-04-01)
  [2703] Lua Metatables - (2010-04-02)
  [2710] __index and __newindex in Lua - metatable methods - (2010-04-05)
  [3142] Private and Public - and things between - (2011-01-22)
  [3396] Tables as Objects in Lua - a gentle introduction to data driven programming - (2011-08-17)
  [3524] Metaclasses (Python) and Metatables (Lua) - (2011-11-17)
  [3683] Weak references in Lua - what are they, and why use them? - (2012-04-04)
  [3694] Special __ methods you can use in Lua metatables - (2012-04-12)
  [3727] Using Lua tables as objects - (2012-05-11)
  [3730] What is a metatable? How do I set one up? How do I use them? Lua - (2012-05-12)
  [4117] Is Lua an Object Oriented language? - (2013-06-15)
  [4248] Metatables, Metamethods, classes and objects in Lua - (2014-03-18)
  [4273] Dot or Colon separator between table name and member in Lua - what is the difference? - (2014-05-06)
  [4573] Classic style OO code - in Lua - (2015-11-05)
  [4753] Lua, Tcl, Python, C and C++ courses - at our Melksham HQ or on your site - forward from July 2017 - (2017-07-02)

Back to Lua - using modules to add your own utilities

Previous and next or Horse's mouth home

Forward to Classic style OO code - in Lua

If it's Tuesday it must be Belgium?
Learning not just what a program does, but how to design it in the first place.
repeat until in Lua - a one or more rather than a zero or more loop
Tables with values and code in Lua - looks like an object?
Lua - using modules to add your own utilities
A warm welcome awaits you at Well House Manor, Melksham
Lua - changes to how integers and floats are handled - 5.2 to 5.3
Moderation - and the tendency to over-moderate
Japanese and Malaysian food in Melksham