Question

我认为运行这段代码你会得到我的意思。我想在注册表中注册5个名字（人）。我循环了5次，在每个循环中我有一个变量 newPerson ，它应该保存有关一个人的所有信息，然后被添加到 people 寄存器中。在此示例中，为简单起见，仅注册人员的姓名。问题是，最终所有人都变成了同名：“佩特拉”。我对此有点玩，但无法得到这种行为的合理理由。帮助赞赏！

local people={}
local person={
    name="Johan",
    lastName="Seferidis",
    class="B"
}
local names={"Markus", "Eva", "Nikol", "Adam", "Petra"} --people to register


for i=1, 5 do --register 5 people
    local newPerson=person
    local name=names[i]
    for field=1, 3 do --for each field(name, lastname, class)
        if field==1 then newPerson["name"]=name end --register name
    end
    people[i]=newPerson
end

print("First person name: " ..people[1]["name"])
print("Second person name: "..people[2]["name"])
print("Third person name: " ..people[3]["name"])

Answer 1

这里最重要的是Lua变量“包含”一个表实际上只包含对表的引用。复制包含表的变量只会将引用复制到该表，因此表示与此示例中相同的表：

a={"x","y","z"}
b=a
b[2]="Q"
print(a[2]) -- returns Q and not y. Why is easily seen by doing:
print(a,b) -- returns table: 0xXXXXXX 0xXXXXXX indicating it's the same table

如果你真的想要一份表格副本，你需要求助于http://lua-users.org/wiki/CopyTable

Answer 2

试试这个：

local people={}
local names={"Markus", "Eva", "Nikol", "Adam", "Petra"} --people to register

for i=1, 5 do
    people[i]={
        name=names[i],
        lastName="Seferidis",
        class="B"
        }
end

Answer 3

您似乎正在尝试将person用作prototype object。以下是对代码的一些更改，这些更改添加了new函数以便于对象原型设计。

object = {}
function object:new(o)
    -- use the table provided, or create a new table
    o = o or {}
    -- use this object as a prototype
    setmetatable(o, self)
    self.__index = self
    return o
end

local people={}
local person=object:new({name="Johan",lastName="Seferidis",class="B"})

local names={"Markus", "Eva", "Nikol", "Adam", "Petra"} --people to register

for i=1, 5 do --register 5 people
    local newPerson=person:new({["name"]=names[i]})
    people[i]=newPerson
end

print("First person name: " ..people[1].name.." "..people[1].lastName.." "..people[1].class)
-->First person name: Markus Seferidis B

print("Second person name: "..people[2].name.." "..people[2].lastName.." "..people[2].class)
-->Second person name: Eva Seferidis B

print("Third person name: " ..people[3].name.." "..people[3].lastName.." "..people[3].class)
-->Third person name: Nikol Seferidis B

Lua：为什么改变一个变量的值也会改变另一个变量的值？

3 个答案: