【入门夯实】__concat拼接元方法：表参与拼接的回退机制

local player = { name = "甲", level = 60 }
print("玩家信息：" .. player)

local mt = {
    __concat = function(a, b)
        local ta = type(a) == "table" and a.name or a
        local tb = type(b) == "table" and b.name or b
        return ta .. "|" .. tb
    end,
}
local p = setmetatable({ name = "甲" }, mt)
local line = "攻城报名：" .. p .. "|状态：已确认"
print(line)

local info = p .. "|已确认"

__tostring = function(t)
    return "玩家(" .. t.name .. ")"
end,
__concat = function(a, b)
    return tostring(a) .. tostring(b)
end,