Function 在计算机辅助Lua中使用并行函数时的变量重置

我是一个在ComputerCraft（Minecraft）中设计Lua程序的初学者，该程序在玩家第一次使用它时会询问他们的名字，并记录下来。现在，我需要一个程序来检测变量

firstname

是否等于nil，并询问名称是否等于nil。如果变量不等于nil，则表示不需要注册。我当前只有在从主菜单中按

5

后才调用

register（）

问题是每次我在收到提示时将字符串指定给

firstname

，当主菜单出现时，

firstname

返回到nil。我甚至把

print（firstname）

放在菜单的末尾来测试这一点

我假设这是由于这一切都运行在并行函数中。我并行运行

main menu（）

和

Controls（）

，以便可以同时收听键盘输入和红石输入

在保留变量的同时，如何保持函数侦听和菜单工作

以下是完整的代码：

    rednet.open("back") --Opens rednet on the back side of computer

    local innerdooropen = false --Stuff to do with the airlock
    local outerdooropen = false

    function reset()  --A handy function for screen reset
      term.clear()
      term.setCursorPos(1,1)
    end

    local function register()  --This is the registration menu system
        if firstname == nil then
            print "Welcome to Obsidian Station!"
            print "You must register before entering"
            print "Please type your first name"

            local firstname = read()

            if firstname ~= "" then
                print("Enter your last name")
                local lastname = read()
                    print("You are now registered "..firstname.." "..lastname)
                    sleep(3)

                    rednet.broadcast(firstname.." "..lastname)

            elseif firstname == "" then
                print "You must register to enter"
                shell.run("startup")
            end
        end
        if firstname ~= nil then
            print("Registration Not Needed")
            sleep(2)
        end

    end

    --Beginning of Section You Don't Have to Read        
    local function MainMenu()
    while true do
    term.clear()
    term.setCursorPos(1, 1)
    if innerdooropen == true then
        rs.setOutput("left", false)
    end
    if outerdooropen == true then
        rs.setOutput("right", false)
    end
    if innerdooropen == false then
        rs.setOutput("left", true)

    end
    if outerdooropen == false then
        rs.setOutput("right", true)
    end




    print "Safety Airlock Control"
    print "~~~~~~~~~~~~~~~~~~~~~~"
    print "[1] Open Outer Door"
    print "[2] Open Inner Door"
    print "[3] Close Both Doors"
    print ""
    print "[4] Open Both Doors - WARNING! DANGEROUS!"
    print ""
    print "[5] Register"
    print(firstname)

    input = read()

    if input == "2" then
      print "Inner Door Open"
      outerdooropen = false
      sleep "1"
      innerdooropen = true

    end

    if input == "1" then
      print "Outer Door Open"
      innerdooropen = false
      sleep "1"
      outerdooropen = true
    end

    if input == "3" then
      print "Both Doors Closed"
    innerdooropen = false
    outerdooropen = false
    end

    if input == "5" then
        reset()
        register()
    end
    if input == "6" then
        print("firstname: "..firstname)
        sleep(3)
    end

    if input == "4" then
      term.clear()
      term.setCursorPos(1, 1)
      print "CONFIRM BOTH DOORS OPEN? [y] [n]"
      input = read()
      if input == "y" then
        print "OPENING AIRLOCK DOORS IN"
        sleep "1"
        print "10"
        sleep "1"
        print "9"
        sleep "1"
        print "8"
        sleep "1"
        print "7"
        sleep "1"
        print "6"
        sleep "1"
        print "5"
        sleep "1"
        print "4"
        sleep "1"
        print "3"
        sleep "1"
        print "2"
        sleep "1"
        print "1"
        sleep "1"
        innerdooropen = true
        outerdooropen = true
        print "DOORS OPEN"
        sleep "1"
      end
     elseif input == "n" then
       term.clear()
       term.setCursorPos(1, 1)
       shell.run("startup")
     end

    end
    end

    --end of section you don't have to read

    local function Controls()
        while true do
                local e = os.pullEvent()
                if e == "redstone" and rs.getInput("bottom") then
                        redstone.setOutput ("left", true)
                        sleep "1"
                        redstone.setOutput ("right", false)
                        innerdooropen = true
                        outerdooropen = false
                end
        end
    end
    while true do
       parallel.waitForAll(MainMenu,Controls)
    end

---

在并行外部初始化firstname。将

local firstname

放在代码顶部，将

local firstname=read（）

更改为just

firstname=read（）

，并对姓氏执行相同的操作

在检查变量是否为nil后，您将创建该变量，这就是它总是返回nil的原因。类似地，当函数结束时，firstname不再存在，因为它是在函数内部调用和创建的。所以它总是返回零。 代码的顶部应该是这样的

rednet.open("back") --Opens rednet on the back side of computer

local innerdooropen = false --Stuff to do with the airlock
local outerdooropen = false
local firstname = ""
local lastname = ""

另一部分应如下所示：

        if firstname == nil then
        print "Welcome to Obsidian Station!"
        print "You must register before entering"
        print "Please type your first name"

        firstname = read()

        if firstname ~= "" then
            print("Enter your last name")
            lastname = read()
                print("You are now registered "..firstname.." "..lastname)
                sleep(3)

---

在并行外部初始化firstname。将

local firstname

放在代码顶部，将

local firstname=read（）

更改为just

firstname=read（）

，并对姓氏执行相同的操作

在检查变量是否为nil后，您将创建该变量，这就是它总是返回nil的原因。类似地，当函数结束时，firstname不再存在，因为它是在函数内部调用和创建的。所以它总是返回零。 代码的顶部应该是这样的

rednet.open("back") --Opens rednet on the back side of computer

local innerdooropen = false --Stuff to do with the airlock
local outerdooropen = false
local firstname = ""
local lastname = ""

另一部分应如下所示：

        if firstname == nil then
        print "Welcome to Obsidian Station!"
        print "You must register before entering"
        print "Please type your first name"

        firstname = read()

        if firstname ~= "" then
            print("Enter your last name")
            lastname = read()
                print("You are now registered "..firstname.." "..lastname)
                sleep(3)

---

在检查firstname是否等于nil之前，应该初始化firstname

local firstname = nil; --Move this up here so that you can access it elsewhere.
local lastname = nil; --This is also needed out here.

local function register()  --This is the registration menu system
    if firstname == nil then
        print "Welcome to Obsidian Station!"
        print "You must register before entering"
        print "Please type your first name"

        firstname = read() --Change this to just setting firstname to the read name.

        if firstname ~= "" then
            print("Enter your last name")
            lastname = read()
                print("You are now registered "..firstname.." "..lastname)
                sleep(3)

                rednet.broadcast(firstname.." "..lastname)

        elseif firstname == "" then
            print "You must register to enter"
            shell.run("startup")
        end
    end
    if firstname ~= nil then --Now this will not error as well.
        print("Registration Not Needed")
        sleep(2)
    end

end

这允许在其他地方访问firstname，而不仅仅是在firstif语句中。您正在检查未初始化的变量是否等于nil

---

编辑：看到了purxiz的答案，意识到您可能也希望lastname位于循环之外。我现在在上面的代码中修复了它。

在检查firstname是否等于nil之前，应该初始化firstname

local firstname = nil; --Move this up here so that you can access it elsewhere.
local lastname = nil; --This is also needed out here.

local function register()  --This is the registration menu system
    if firstname == nil then
        print "Welcome to Obsidian Station!"
        print "You must register before entering"
        print "Please type your first name"

        firstname = read() --Change this to just setting firstname to the read name.

        if firstname ~= "" then
            print("Enter your last name")
            lastname = read()
                print("You are now registered "..firstname.." "..lastname)
                sleep(3)

                rednet.broadcast(firstname.." "..lastname)

        elseif firstname == "" then
            print "You must register to enter"
            shell.run("startup")
        end
    end
    if firstname ~= nil then --Now this will not error as well.
        print("Registration Not Needed")
        sleep(2)
    end

end

这允许在其他地方访问firstname，而不仅仅是在firstif语句中。您正在检查未初始化的变量是否等于nil

---

编辑：看到了purxiz的答案，意识到您可能也希望lastname位于循环之外。我现在在上面的代码中修复了它。

当然。这很有道理。谢谢你尽可能清楚地解释这一点。当然。这很有道理。感谢您尽可能清楚地解释这一点。