Lua

免费赠送一个让Lua Table变成只读的代码，如果使用Lua作为配置表，有必要让table变成只读的，防止运行时被误改。此题也是我对有Lua使用经验者的应试者常用的面试题:) local M = {} local function readOnlyTableIter_pairs(t, k) local v k, v = next(t.__readonly, k) if v ~= nil then return k, v end end local function readOnlyTableIter_ipairs(t, i) i = i + 1 local v = t.__readonly[i] if v ~= nil then return i, v end end function M.MakeReadOnly(t) assert(type(t) == "table", "except table at parameter 1") assert(getmetatable(t) == nil, "table already has metatable") for k, v in pairs(t) do if type(v) == "table" then t[k] = M.MakeReadOnly(v, includeChildren) end end return setmetatable({__readonly=t}, { __index = t, __newindex = function() error("Can't modify read-only table") end, __pairs = function(_t) return readOnlyTableIter_pairs, _t, nil end, __ipairs = function(_t) return readOnlyTableIter_ipairs, _t, 0 end, __len = function(_t) return #_t.__readonly end, __metatable = false, }) end return M