Lua notes

📃 These are primarily notes, intended to be a collection of useful fragments, that will probably never be complete in any sense.

Variables

types and conversions

✎ This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

nil
boolean
number  always (float)
string
function
userdata
thread
table

You'll also find frequent use of

Casting and coercion

• tostring

note that .. coerces things to strings

if something has a __tostring" field, it will be called(verify)

you may sometimes want string.format for more control, which is a printf-alike

If the metatable of e has a

• tonumber(e [, base])

• string.byte(s, i)[1]

return characters as number

• string.byte(s, i,j)[2]

return characters as list of numbers

Conventions

CamelCase for classes, factories

underscores for objects, instances, functions,

Operators

Aside from + - * / and %, there is also ^ (pow)

Boolean

and
or 
not 
==   equal to
~=   not equal to
<
>
<=
>=

Also

#    length of table or string
..    string concat

Bitwise operators

See also:

• http://lua-users.org/wiki/BitwiseOperators

String manipilation

http://www.lua.org/manual/5.1/manual.html#5.4

Errors

function or expression too complex

Often amounts to 'too many arguments' (the VM has only so many registers)

In that case, the fix is often "pass an array" and/or "build that array in chunks".