Lua Code Conventions

  • Be consistent.
  • Indent using spaces, two wide. Do indent properly.
  • Try to limit width of the code to 80 chars.
  • Don't add spaces between braces/brackets and what's in them.
  • Do use brackets in functions calls even if it's not necessary.
  • Name variables for what they are, don't include type markers in them, i.e. do not use Hungarian notation.
  • Nice to have: sort your requires alphabetically (OCD!)
  • Only comment if it's something complicated/non obvious. Keep in mind that comments increase file size, which increases the amount of RAM required to load your program!
  • If you have to validate arguments, use the built-in checkArg method. Homogenous error messages are a good thing! Its usage is checkArg(n, value, type1, …), where n is the number of the argument, value is the value of the argument and type1 and so on are the allowed types for the argument, as retrieved via type(value). The number is used in the error message like so: “bad argument #n (type1 expected, got type(value))”. So for example, to require the first argument to be a number you'd do checkArg(1, arg, “number”).

Bad Code:

function f(sArg1 , ... )
   assert(type(sArg1)== "string", "me wants a strign!")
    if sArg1 then
        local nResult = 1
        --do some more stuff
        return nResult
if  f ( "a" )  ==1 then

Good Code:

function f(name, ...)
  checkArg(1, name, "string")
  if name then
    local result = 1
    -- We extrapolate the b-spline of the non-euclidean space to
    -- determine the fraction of potential failures encountered.
    return result
if f("a") == 1 then