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Lua

tip
  • 使用最广的脚本语言之一
caution
  • 不能直接为 Table 添加额外方法, 因为每个 Table 都有自己的 Metadata
-- 自定义加载目录
package.path = package.path .. ';/data/lua/?.lua'
T = require("t")

-- dotfile 可以直接使用绝对路径
dofile("/data/lua/my")

语法​

-- 类
Dog = {}

function Dog:new()
  local newObj = {sound = 'woof'}
  self.__index = self
  return setmetatable(newObj, self)
end

function Dog:makeSound()
  print('I say ' .. self.sound)
end
-- : 等同于
function Dog.makeSound(self)
  print('I say ' .. self.sound)
end

-- 继承
LoudDog = Dog:new()

-- 可选
function LoudDog:new()
  local newObj = {}
  -- 初始化 newObj
  self.__index = self
  return setmetatable(newObj, self)
end
function LoudDog:makeSound()
  local s = self.sound .. ' '
  print(s .. s .. s)
end

-- mod.lua
local M = {}
function M.func()
  return true
end
return M

-- 依赖模块
-- require 会缓存
-- dofile 不会缓存
-- loadfile 不执行，返回函数 - 类似于 loadstring
local mod = require('mod')
-- 等价于
local mod = (function ()
  -- mod.lua 内容
  local M = {}
  function M.func()
    return true
  end
  return M
end)()

metatable​

  • 元表 - 操作重载

| method | demo | | --------------------- | --------- | ---------------------- | | __add(a, b) | a + b | | __sub(a, b) | a - b | | __mul(a, b) | a * b | | __div(a, b) | a / b | | __mod(a, b) | a % b | | __pow(a, b) | a ^ b | | __unm(a) | -a | | __concat(a, b) | a .. b | | __len(a) | #a | | __eq(a, b) | a == b | | __lt(a, b) | a < b | | __le(a, b) | a <= b | | __index(a, b) | a.b | fn(tbl,key) or a table | | __newindex(a, b, c) | a.b = c | | __call(a, ...) | a(...) | | __gc | | | __close | | | __mode | | | __name | |

Helper​

---------------------------------------------
---- Lua Table Helper
---------------------------------------------
local table_meta = { __index = table }
function T(t)
    -- returns the table passed as parameter or a new table
    -- with custom metatable already set to resolve methods in `table`
    return setmetatable(t or {}, table_meta)
end

table.T = T

function table.filter(tab, f)
    if type(f) ~= 'function' then
        local _v = f
        f = function(v, i) return v == _v end
    end

    local t = T {}
    for k, v in pairs(tab) do
        if not f(v) then
            t[#t + 1] = v
        end
    end
    return t
end

function table.map(tab, fn)
    for k, v in pairs(tab) do
        tab[k] = fn(v, k)
    end
    return tab
end

function string:split(sep)
    local sep, fields = sep or ",", T {}
    local pattern = string.format("([^%s]+)", sep)
    self:gsub(pattern, function(c) fields[#fields + 1] = c end)
    return fields
end

return T