Lua 特性速览（简略）

此文迎合有点语言基础的人速度浏览Lua特性的需求

function 不定长参数

function getSumMore(...)
    local sum=0
    for k,v in pairs{...} do
        sum =sum +v
        end
    return sum
   end
io.write("Sum",getSumMore(1,2,3,4,5,6,7),"\n")

function is variable

like anonymous function

doubleIT = function(x) return x *2 end

Intersting Closure

function outerFunc()
    local i=0
    return function()
        i=i+1
        return i
    end
end
getI=outerFunc()
print(getI())
print(getI())

Coroutine

co = coroutine.create(function()
    for i=1,10,1 do
        print(i)
        print(coroutine.status(co))
        if i==5 then coroutine.yield() end
    end
end)

print(coroutine.status(co))
coroutine.resume(co)
print(coroutine.status(co))

co2 =coroutine.create(function()
    for i=101,110,1 do
        print(i)
        end end)

coroutine.resume(co2)
coroutine.resume(co)
print(coroutine.status(co))

files_IO

--r:Read only(default)

--w: Overwrite or create a new file

--a: Append or create a new file

--r+: Read & write existing file

--w+: Overwrite read or create a file

--a+: Append read or create file

file =io.open("test.lua","w+")
file:write("Random string of text\n")
file:write("Random string of text\n")
file:seek("set",0)
print(file:read("*a"))
file:close()

file =io.open("test.lua","a+")
file:write("Even more text\n")
file:seek("set",0)
print(file:read("*a"))
file:close()

modules

convertModule = require("convert")

print(string.format("%.3f cm",convertModule.ftToCm(12)))

local convert={}
function convert.ftToCm(feet)
    return feet +30.48
end
return convert

metaTable 操作符的重载？

aTable={}
for x=1,10 do
    aTable[x]=x
end

mt={
    __add = function(table1,table2)
    sumTable={}
    for y=1,#table1 do
        if(table1[y]~=nil) and (table2[y]~=nil) then
            sumTable[y]=table1[y]+table2[y]
        else
            sumTable[y]=0
        end
    end
    return sumTable
    end,
    __eq = function(table1,table2)
        return table1.value ==table2.value
    end,
    __lt = function(table1,table2)
        return table1.value <table2.value
    end,
    __le = function(table1,table2)
        return table1.value <=table2.value
    end,
}

setmetatable(aTable,mt)
print(aTable==aTable)

addTable={}
addTable =aTable+aTable

for i=1,10 do
    print(addTable[i])
end

Fake Class

Animal={height=0,weight=0,name="No name",sound="No Sound"}

function Animal:New(height,weight,name,sound)
    setmetatable({},Animal)

    self.height=height
    self.weight =weight
    self.name=name
    self.sound=sound

    return self
end

function Animal:toString()
    animalStr =string.format("%s weight %.1f lbs,is %.1f in tall and says %s",self.name,self.weight,self.height,self.sound)
    return animalStr
end

spot = Animal:New(10,15,"Spot","Woof")
print(spot.weight)
print(spot:toString())

Inheirtance

继承上面的~

function Cat:toString()
    animalStr =string.format("%s weight %.1f lbs,is %.1f in tall and says %s and loves %s",self.name,self.weight,self.height,self.sound,self.favFood)
    return animalStr
end

fluffy = Cat:New(10,15,"Fluffy","Meow","Tuna")
print(fluffy:toString())