local format = string.format local function as_char(v, prio) if type(v) == 'table' and v.name then return (v.prio < prio and format("(%s)", v.name) or v.name) end return tostring(v) end local var_name local var_name_mt = { __add = function(a, b) return var_name(format("%s + %s", as_char(a, 0), as_char(b, 0)), 0) end, __mul = function(a, b) return var_name(format("%s * %s", as_char(a, 2), as_char(b, 2)), 2) end, __sub = function(a, b) return var_name(format("%s - %s", as_char(a, 0), as_char(b, 0)), 0) end, __div = function(a, b) return var_name(format("%s / %s", as_char(a, 2), as_char(b, 2)), 2) end, __pow = function(a, b) return var_name(format("%s^%s", as_char(a, 10), as_char(b, 10)), 10) end, __unm = function(a) return var_name(format("-%s", as_char(a, 1)), 1) end, } var_name = function (name, prio) local t = {prio= prio or 10, name= name} return setmetatable(t, var_name_mt) end return var_name