Lua

• lua/lua
• 5.4/manual

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