function checkVarClass(var, class, message)
    if type(var) ~= "table" or var["class"] == nil or not var:isInstanceOf(class) then 
        throw(message == nil and "Wrong variable class." or message, 1, true)
    end
end

function accessorFunc(tbl, varName, name, defaultValue)
    tbl[varName] = defaultValue
    tbl["get" .. name] = function(self) return self[varName] end
    tbl["set" .. name] = function(self, value) self[varName] = value end
end