4.6 Function Definitions

Functions in Lua can be defined anywhere in the global level of a module. The syntax for function definition is:

   function ::= function var '(' [ parlist1 ] ')' block end

When Lua pre-compiles a chunk, all its function bodies are pre-compiled, too. Then, when Lua ``executes'' the function definition, its body is stored, with type function, into the variable var.

Parameters act as local variables, initialized with the argument values.

   parlist1 ::= 'name' { ',' name }

Results are returned using the return statement (see Section 4.4.3). If control reaches the end of a function without a return instruction, the function returns with no results.

There is a special syntax for definition of methods, that is, functions which have an extra parameter self.

   function ::= function var ':' name '(' [ parlist1 ] ')' block end

function v:f (...)
  ...
end

function v.f (self, ...)
  ...
end